Normally, I'd advise transmission servicing and software updates. You've already had that done.
You aren't too far away from Horton cars based on your profile location. Roughly an hour and a half away maybe (that's just a search on Google maps, but how accurate that is I don't know). Its a bit of a trip I know, but these guys really know their stuff.
It may be worth giving them a call to see what they say. Describe the symptoms to them and take it from there.
There's lots of things that can cause a transmission issue, which aren't an integral part of the transmission. You're right about ABS rings, that can affect it or even loose bolts on a driveshaft.
Horton Cars
Unit 1 & 2, Thame Road Oakley, Bucks, HP18 9QQ
Tel: 01844 239308
Have a read of these articles on Horton's website.
https://hortoncars.com/volvo-news/vo...and-solutions/
https://hortoncars.com/latest-news/v...arbox-repairs/