Can't save widgets with a custom functions.php file

Hey all,

So I’m doing some freelance work on an upgrade for an existing website. On their current website they have 4 custom php classes totalling over 6000 lines of code, these classes are used to display a custom store locator as well as changing some fields in the wp-admin backend.

As soon as I comment out the code that loads these files I can store and use my widgets with no issues, as soon as the code is back in the widget areas remain but anything that was inside them gets removed and I can no longer store things inside the areas.

Does anyone have an idea of where I should even start, my first though was that somewhere it was overwriting the widget hook or something similar but I can’t see anything that points to that.

Any advice would be great as I’m dreading sifting through all of this code to fix the issue.

Thanks!