XF 2.0 Font Size Automatically Changing

[MegaPixel]

We've been working on adjustments preparing my forum, we have a test forum and a live forum. However, we've noticed on the Development Forum an issue based on font size of test.

If we post a new thread with text size of 26, save it. But then if you edit the thread/post, it's changed to font size 22.
If we post a new thread with text size of 22, save it. But then if you edit the thread/post, it's changed to font size 15.
If you keep editting the thread and saving it without changing the font size back, it just gets smaller...

It definitely looks board-specific as I can't replicate it anywhere else, but I've also compared it to our live forum (not yet in use) and that doesn't have the issue.
Is there any suggestions of any templates/settings I could begin looking at? I've compared a bunch of them from our working site to this not-working site and was unable to find any irregularities.

 

[MegaPixel]

Can replicate this on other browsers/machines too.
I tried exporting the forum that doesn't work onto the one that does, no difference.
Disabled any addons, and even tried moving the addons onto the one that does work.
I copied the extra.css from the none-working forum to the working-forum to see if there's any issue inthere.

Not had much look/unsure where else to look to try to isolate the cause. Any suggestions appreciated.

P.s. can this be moved into Troubleshooting and Problems.. noticed I posted in wrong section, apologies.

 

[sbj]

In such cases it is usually addons causing the problems.
Are you using any addon on your development forum? The editor manager is a popular one and it has configurations about font sizes for example.
The other thing I can think of is that you have in your extra.less codes to change font-sizes for specific areas. Did you check them?