#Mastodon experts: I have spent a couple hours in #RTFM but am unable to solve this...

I have the Advanced Web Interface enabled but am no longer able to open more than three columns in Mastodon. I have reproduced the problem in different browsers and with my adblock disabled.

This worked when I first joined but suddenly stopped, without a browser update etc. This makes me think I've accidentally flipped a preference other than Advanced Web Interface, but I can't find any others that seem relevant.

I've also tried switching off the advanced mode and verifying that it goes to single column, then back, but it still only wants three max.

Any ideas? Thanks!