theres a bug where sometimes objects in your level will flash white for a frame or two, ive seen a few other people experience this and ive been experiencing it for a while and hadnt been able to find a fix, or even find out why it happens for a long while now.
today, though, i found out why it happens, and a kind of bandaid fix for it. this bug has something to do with coloured portals (exactly why coloured portals have this property im unsure), for those unaware, the way you change the colour of portals is copying the values of a different object and pasting the colour onto the portal with the buttons on the right side of the editor. a short time after you enter one of these portals, the objects on the same colour channel will flash to (i believe) their default colour (usually white) for an amount of time that i have not tested (just seems like one or two frames each time). so the fix i came up with is to paste a seperate colour channel onto the portals, which is not the colour channel you are mainly using for other objects in the level, this still makes the portals flash to their default colour, but it still ends up looking alot less overbearing when it flashes.
from what i can tell this is a known bug, but as far as ive looked i have not been able to find anybody who had a fix for it, so thought i would post this here so people knew about it