It's still happening in 1.18.2
The problem seems to have dissapeared.
This bug still presist in 1.14.30 I was trying to make a custom trade for an custom entity in my realm but the wandering trader's trade will disappear. The interesting part is when the custom entity has the wandering trader's trade file the wandering trader doesn't lost its trade but when I change it to something else like a custom trade or the butcher's trade the wandering trader's trade will dissapear.
I just updated to beta just now same thing keeps happening to me but when I turn off my wifi or mobile data it does not crash anymore.
Yes I just tested it and It still happens in 1.20.1