I have the same watch (the 2019 iteration) and I am having similar issues to those you detailed; the leather/deployant factory fit strap does not fit perfectly. I bought it with the standard strap and had this changed to a small strap but the clasp still ...
I ordered 70 x 105mm, and it fits perfectly. Maybe a little too perfectly, as it is short enough I snipped off the second keep, as it didn't do anything. I would consider going a bit larger, but the advantage to 70x105 was that it was a standard size, and...