I've just upgraded to SugarCRM 188.8.131.52.
In my Leads module I have a custom checkbox field.
When the checkbox is checked few other fields have to be visible.
This was working fine in version 184.108.40.206
I'm using formula equal($is_onboarding_c,true)
After upgrade the fields are hidden even though the checkbox is checked (I can see it in web developer tool).
I tested using the formula with a field that is not a checkbox field e.g. equal($first_name,"Tolek") and it works correctly.
It looks like a bug.