You want your tape width to be slightly wider (2-3mm) than the internal width, so it part way up the side walls. If you’ve not already done that, it’s worth trying.
I'll have a look. The stuff I have is for 25mm rims which is wider than the rim I have.
It's almost certainly my cack handedness. Though I take on board testers point about the rim.
Yeah. Reading the spec they suggest that rim tap.