We have a 2020 isata3 built on a 2018MBS and have lost one rear cap as well. Seems to be pressure applied so expect to lose second one on the next rough road passage. I have seen others that suggest various methods to secure but I feel hub cap is mostly for show and clean lines.
2020 Dynamax Istata 3
Newbie to RVing and looking forward to the experiences and meeting others during the journey