"Things are often not as simple as they seem ... "

I am on a hill. Uphill neighbor is a little chapel that's run kinda
like a slumlord rental. 3 or 4 years ago I had similar water problem.
Could actually see small column of water shooting out of hole in
basement floor. Looked everywhere, couldn't find leak. Finally
got a city water inspector to come out, assuming water main break
or somesuch. Turns out the derelicts in the chapel had a plumbing
problem. I had to get the city alder-critter to help force them to
(allegedly) fix it.

water coming up from under floor? happened before but you never
metioned it.....

if water from that source can get in any can, time for a interior
french drain ...........