Issues with Google's apps on iOS over Cellular
Tetsujin's answer helped me, although my problem wasn't exactly the same as his. Google and Google maps weren't yielding results, and I blamed my service provider for crappy coverage, although other apps were working. I went into Settings -> Cellular as per Tetsujin's instructions, and found that Google and Google maps were turned off under "Use cellular data for"... Turned them back on, and they now work. When setting up my phone, I had set up Google apps conservatively to keep the MoFos from snooping on me. Turns out that totally invalidates them when not on wifi....