I can't stop my vacation because I customized my board!

I started short vacation a few days ago. Now that I returned, I try to finish it. But I can't: while saving prefs I get the following message

Oops?! We noticed the following errors in your form:
This game board is restricted to Premium Members only.

WTF?

Are you trying to use the 3D board? That's for premium members only I think.

I changed background in the past. Still, I don't understand why I get this message while the only thing I am trying to do is to switch my vacation off.

Make sure the piece style in your online chess settings isn't the 3D pieces, if they're not, then I don't know what to suggest.

This is even more irritating: I am still on vacation, the system promptly shows that but ... I just timed out two games (in the tournament which started while I was on vacation). Grrrrrrrr wrrrrrr.

I don't use 3D pieces. Will try shifting background, maybe it will help.