All lights off (Hue) stopped working

We have a Hue connected, working just fine (with Mueller RGBWW lamps). Today I experimented with IFTTT, having Hue perform some light scenes. After this, the Homey flows with ‘All lights off’ don’t work anymore? I have reinstalled Hue-app in Homey, but no improvement.

Does anyone perhaps had similar experiences, and then perhaps solutions? I could try resetting Hue, re-enter all lamps, etc. but would prefer skipping this of course; this will take some time, and I highly doubt if this would resolve this issue. I hope someone can help …

Ps. Homey flows initiating Hue-scenes, still work.
Command ‘all light off’ in Hue itself, also works.