Gmail search giving little to no results

[nzoomed]

Seen similar if the conversation view is being used some things dont work. Can't remember the exact solution, but from memory, disabling conversation gave better results. One thing I do remember though, the person was using web mail = with poor results, and stated using Outlook ( 365) loaded gmail - worked much better.

Bit of a long shot but who knows

Like king dont really use gmail for anything serious, its to inconsistent and they seem to change things for no real reason, often causing more problems. I use my business domain email. 100% works 

Interesting that conversation view may have a bearing on it.
Should play around with that to see if it makes any changes or else I should just add the account to my Thunderbird. 
I don't use Gmail for my main address and have my own domain that I just use pop3 through Thunderbird for most of my communication.
I see a fair few that run their domains email through Google apps which essentially is putting your own address through the Gmail system.
Would be interested to see if those users are affected.