Using a HPE2023, running 10.0.0.rc105 using version 7.0.1.1201 of the app (iOS).
I am running version 3.2.4 of the group app.
I have a light group which was added on version 3.1.3, it uses the capabilities turned on, dim, light mode, hue, saturation, temperature.
All capabilities are set to “average value” except on/off which is set to “any”.
There are four devices in the group, and when I attempt to add or remove a device from the group - it works perfectly.
I also confirms, added-removed several device types and always worked fine, including older groups.
Hi Jamie, I’m using an HP2019 and version 3.2.4 of the app. I create 2 virtual lights and a group where I place them. If I delete one of the two virtual lights from Homey without removing it from the group first, I won’t be able to modify the group anymore. On the repair screen, I see the error [device_not_found]. I’ve tried repeating this operation several times (creating new lights and new groups), and sometimes I managed to modify the group only once. I’ve created a report (00413d10-4298-4fd8-a075-d5412fcea72a), hoping it can help you. Let me know if you need any further information 
Well you make it sound more special them it is hahaha.
I use the hp2019 with app version 3.2.4, when I try to repare I got the same error, on the same way as pmeester, but with bulbs.
I can’t repair the group because the bulb has been delete.
So I have to delete the complete group en make a new one.
the group is a lamp type. Made in version 2.5.301, maybe that’s the problem. I don’t know if this happen with the New groups
Good morning Jamie, after a Homey restart, some groups fail to synchronize their state with their respective devices.
I’ll try to provide you with as much information as possible to help you understand the problem. I hope everything is clear. I apologize if there are any grammatical errors, but I’m not good at writing in English 
I have a group of lights called “Faretti Bagno” that contains 4 Philips Hue bulbs [Faretto Bagno 1, Faretto Bagno 2, Faretto Bagno 3, Faretto Bagno 4].
The group is set to “on if any devices are on,” but after the Homey restart, the group stopped synchronizing with some of its devices.
For example, in the last test I performed, if I turn on “Faretto Bagno 1” or “Faretto Bagno 4,” the group that contains them doesn’t change its state. The “Faretti Bagno” group only synchronizes its state with “Faretto Bagno 2” and not with the other devices. It seems as if it has lost the registration for some events.
The issue doesn’t occur for all groups; some of them work perfectly. After that, I restarted the app, and all groups responded correctly to state changes.
Afterward, I conducted another test.
I disabled the Group app and restarted Homey. I waited for all the apps to initialize properly and then launched Group.
In this scenario, all the groups worked correctly, and it was not necessary to restart the app.
I’m using an HP2019 with version 8.1.4.
I’m also using version 3.2.4 of the app, and I recreated all my groups with this latest version.
Before running the test, I made sure that all apps were correctly launched.
I generated a report regarding this issue: 2fec177a-0e6f-4139-a796-01d0b46b5eda
If you need any further information, feel free to ask. Thank you!
thank you for the detailed reports, very useful. When I get some time I will use it to help replicate the bug and hopefully fix it.
Thanks again
Is there any news on this?
I haven’t received any follow-up on that.
Hello.
My first post on the forums…
I have the same issue and have come to the same conclusion. If a device is removed from Homey without being removed from the group first that group can no longer be edited.
In older version of editing groups there would be a red cross and the label [Deleted] I kind of remember. You just unchecked the box and the device was gone from the group and everything kept on working.
I hope this issue can be fixed because i have built a huge portion of my setup on groups and it has worked so great in the past.
/Mikael in Sweden
well, another try
All my groups are made in app version 3.2.4
i have 2 different lamp groups, which are switched on and off with 1 other lamp group (lampen beneden)
(So i put on the last group, all the other groups are turned on. See first picture)
When i delete the “lamp TV Group” and make a new one, i get the error message when i want to add the new group to the “lampen beneden”
Error message, see last picture
So now i have to delete the group “lampen beneden” and make it again.
I also have to repair the flows with “lampen beneden” in it.
I have the hp early 2019
this is very annoying
hope i gave you enough information.
Report code 7dfa9b4b-7e72-47fd-a234-bc715d5df070
I’m not sure I understood you, are you trying to create nested groups? This is not supported anymore.
For repairing flows, check my comments above, there is script for that (not perfect but at least not needed to fix all flows manually)
Also error messages in other language then English, are not helping much - developer is from AU
Nested groups are possible with the “other” groups - aka advance groups.
Yes I believe I have enough information, but I recently started a new job and haven’t had any mental space available to work on my hobbies.
When I get some spare available time I will look into it, fixing this is possible - there is code in the app to check for deleted items but it must have a bug in it.
No promises as to when I will get the time sorry.
Thanks
I have the same problem… I recreated the device several times because I thought it was my fault. the state is no longer updated. 
