Created attachment 104130 [details] Non-selectable strings in layer blending modes If we apply 'Separate image' function, we have non-selectable strings in layer blending modes. Try select other layer and all works again.
That's because the new layers are grayscale layers, you need to toggle 'output to color not grayscale' if you want all the blending modes to work. I will close this bugreport now as it is not a bug.
(In reply to wolthera from comment #1) > That's because the new layers are grayscale layers, you need to toggle > 'output to color not grayscale' if you want all the blending modes to work. O'key... but all blending modes works correct if we simple reselect layer (no change a color space!). And layers color space is rgb, not grayscale. :) So, it's works but not works right after separation. So — it's a bug, not a feature. Minor bug but may be misleading. P.S. I apologize for my awkward English, this is not my primary language
Created attachment 105182 [details] moving layers and reselect layers Yep! I be not correct, it's grayscale color space... but: — Do you think this works correctly? ;)
In the second video you posted, it looks like applying "Separate image" leads to the same bug I noticed a few months ago. I'll mark this report as a duplicate. *** This bug has been marked as a duplicate of bug 374386 ***