Spent a week on my well/tank/pump system - at a complete loss!

Hey all. Was going to post on Plumbing Zone but looks likes that is limited to professsionals, and it had a link to here to which I already had an account so, here I am. Hope someone can answer a question for me.

Long story short - we bought a house 1.5 years ago with a shallow well (spring fed), pump and tank system that pushes water to 3 water spigots around our yard. I understood it all to be real old maybe original (15 years) equipment but unsure. The pump finally died a couple weeks ago.

I replaced it with the exact same (but much newer, dimensions were a hair off but I survived) make and model pump. Wayne 1/2 HP SWS50.

My system is a little different than you see in diagrams. Usually, it is well -> pump -> tank -> supply lines to everthing. Mine is well -> pump -> supply lines to everything -> tank.

Still, it seems to work fine. The tank runs the water from 50 down to 30psi then the pump turns on and takes over and refills the tank then hands it back over to the tank when 50 is hit again. You feel a slight twitch in water as your using it when it does this and can hear the pump cycle on then off (it's only 34 gallon tank and it is used for gardens etc)

Here's my problem. I have spent the past several days trying to narrow down what I thought was a leak, and this morning I was thrown for a real loop. Basically, the first day after I got it all working again, I came out and turned on water and the pump kicked on, indicating the pressure had been lost and my hopes and dreams of an easy project being crushed. So I then charged it, saw the pressure at 50psi on the line, and waited. 12 hours later I checked it, it was down to 20. (if I remember correctly, but why wouldn't the pump kick on when down to thirty and re pressurize? btw)

So, I charged the line and did it again. Same thing. So, this time I charged the line and cut off 1/2 the system with ball valve that disconnects one side of the property, to try to narrow down. Waited 12 hours. This time no pressure loss at all. I thought I had it figured out. The problem is in that side, obviously, right? The good side that doesn't go under any concrete. I don't mind digging, that's cheap!

But, before I started I wanted to verify. So I opened that side back up, charged the lines back to 50psi, and went to bed. I expected to see loss back down to 20 this am. Then I was going to cut the one side off again, go to work come home tonight and see that none was lost.

Except this morning I get up, and it is still at 50. WTF! No pressure loss this time with both sections turned on.

So my question, because I'm reaching for ANYTHING that even makes sense at this point.. is it possible maybe the tank was over pressurized (3 different pressure guages gave vastly different results when I charged it..) or maybe there were pockets of air in the line or something, and the system needed a few days of use to work out these kinks? Could that explain it? Also, Sunday I took the intake tube completely off to check it and the new footer for leaks which, it had none, and put it back on with better teflon tape. Maybe it had a leak on the one side I can't see that I inadvertently fixed?

I don't have an answer. I could go on for days but if this gets much longer no one will read it. Yesterday my plan was to check the tank with soap for air leak but, had got home to no pressure loss (after having cut off the one side) so I thought it was something on that side but now I'm questioning those findings.

Any ideas? Help!