Indeed, Homey can’t switch more than x (say 3, 4) lights at once, as you’ve discovered.
This flow
should work fine, no need for the 1s delays there. But do connect every flow card error output to the input of the next card in line:
When a light errors, the flow continues.
If the flow also results in random hit and miss, you should inspect your zigbee mesh design.
Also check for wifi interference.
.
If ‘Homey’ means Homey Pro 2023:
You can group those lights with an advanced virtual device for instance.
It sends the on or off commands one by one, instead off all at once.
Looks like this:
