I’ve had ice dams before that bring melted water in through the ceiling….

moisture thru the air (thus the roofing has expanding, blocking access for the water).

When there's no moisture/rain, the roofing 'wood panels' shrink a little thus allowing water to pass ... so this shows (1) don't have enough tar paper on the top surface (underneath the actual shingles, whatever you have on your roof) (2) I am surprised that you have that much 'give and take' on roof shrinkage. I wouldn't normally expect that much of a movement.

Maybe a humidifier too, to put more moisture into the air inside the home?

I remember when I had a leak, and it wasn't the roof, it was the moisture actually seeped through the mortar of my bricks in the home.

So a good tuckpointing job did the trick as well as waterproofing it afterwards.

I'm fixing a hole where the rain gets in
And stops my mind from wandering
Where it will go

Drove me nuts because the drip was at an a/c register about 7 feet down slope from the vent pipe. My gutter guy recommended Geocel ProFlex. Stuffs amazing. It held up to Hurricane Michael and that was several years after I had applied it.

But..

I had a pipe leaking.. but at unpredictable moments.. and never when i was actually using water or when it was raining.

Turned out it was a drain pipe from an upstairs bathtub.. But a previous renovator had noted what I assume was at the time a tiny drip.. and had placed a small plastic wastebasket below it, inside the wall. Over the course of a decade or two.. the leak slowly increased.. but it only became apparent when the water was enough to fill the basket and overflow. And that would evaporate out at different rates.

All of which made for a lot of confusion about how, what and why it was happening until the wall was opened up.