In Advance search: You used to be able to search your custom feilds for a particular invoice. example, custom feild 3 is the job address. This cannot be selected anymore.

I tried this in my sample file and I was able to search using the custom fields, XPH.

You’ll have to make sure that you’ve selected Invoice as the transaction to search for. 

Also, you can check this out for other ways of searching transactions: Find it in QBO. 

If you're still unable to search through custom field, I'd recommend doing it again on a private window. Being able to do it privately indicates a browser issue. With this regard, you can clear your temporary internet files or switch to other browser to fix the issue. 

Let me know in the comments section below if you need anything else.