Can't assign side buttons 3 and 4 on my logitech G502 mouse

[GrootBaas]

Exact behaviour: When prompt opens to ask to hold the button, the prompt detects my button 3 holding it down, but the new selection turns red and nothing is assigned.

[笛野めのん]

If the control settings do not work in-game, try resetting them to default and changing the mouse-side assignments in the mouse driver (multi-button mice should have an included button customisation tool).
I believe you can save/manage multiple profiles, so this will not interfere with other games or OS use if managed properly.

[GrootBaas]

I tried all of that, thanks but still not working

[笛野めのん]

Has the NMS default setting key (e.g. "E") been set in the mouse tool?
Are the settings correct, e.g. one time only/hold?
If you have checked these settings and they are correct, but they do not work, perhaps the side buttons are chattering.
You may want to check if it is responding correctly using the OS mouse operation check tool or a drawing tool.

[AuTo*BK*]

Originally posted by GrootBaas:

Exact behaviour: When prompt opens to ask to hold the button, the prompt detects my button 3 holding it down, but the new selection turns red and nothing is assigned.

I have a G502 as well. The problem is that the game has a middle mouse function that is built in (ie menu drop item) make sure you do reset the game controls then assign all those controls to the 502 in GHUB. make sure that your middle mouse button is set to "middle mouse" and not something else, then you can go in and assign multiple functions without it turning red or just not working.