I don't know whether anyone else experiences this but when playing 960 I encounter some strang things. For one, conditional moves cannot made. The board simply doesn't allow me to move my opponent's piece (and yes, I checked whether the move is legal and tried other pieces as well). The second strange thing is that when I use the analysis board I am stuck with one variation. If I would to swap a move I already played with another one - which I can do just fine with the analysis board pertaining to a regular game - it doesn't allow me to do it. I have to close the window and reopen to look at the next variation.

I tried different browsers - same result.

Interesting, I just tried it myself and everything seems to be in order for me. Anyway, moving this to Help & Support for you so you might find a solution faster.

I just tried it again after your comment. This time things work fine. I have definitely encountered it before so maybe it is one of those computer glitch things where the computer simply needs to sleep for a night to get better.

Maybe so. It's surprising how many problems seem to vanish with a simple restart...

Funny thing was that I didn't do a restart. I simply went to bed and next day it worked normally. But this definitely was not the first time it happened ..

I've also noticed some strange glitches when analyzing moves in 960 games.  But there have been glitches for at least as long as I've been playing 960 games and I've just gotten used to them.  Nothing major, just annoying.

I think I might be having this same problem. Not always, but with one specific 960 game. In the game I can try a move before submitting it, click to undo it, but cannot move any piece after that. And in analysis, I can make as many black and white moves as I want, but if I undo any move, then it gets stuck. Conditional moves also do not work. This started midway through the game and has persisted through a few moves.