I absolutely have had the same problem with my 2019 flextech. I love the bag. However, the shoulder strap and bag are all out of whack, just as you describe. The bag tilts toward the bottom of the bag, clubs up and right, cannot get things even.
I called TM, they mentioned it's been told to cust service. But only suggested I try to pull the straps completely tight in the front then adjust. I've of course done that.
The funny thing is, just after switching to this bag, my shoulder starting killing me. Eventually, pain was so bad I went for MRI. Ends up 3 bulging discs in my neck. I believe the new bag was the culprit or contributed to it.
I LOVE TM products. This bag straps is the worst though.