Tabs not working when upgrade from 7.1 version

[Zuzz]

Today I upgrade heavy customized (in upgrade-safe way, via client/custom and custom/espo/custom) espocrm from v.71.to 8.5 step by step.
I've add panel tabs and them does not work (screenshot in attach).
Please, what i have to verify to fix it ?

[Zuzz]

I add full code of selectTab: function(tab) in custom:views/MODULE/record/detail
And find the reason.
Panels is hided with "tab-hidden" class.
We use custom theme from old version, and it does not contain "tab-hidden" class

[espcrm]

You would need to get that custom theme to support it then? I use Dubas dark theme, it supported it, the light version should also work

[Zuzz]

We try to customize light theme, it's excellent