When I try to dismount a boat with the button (o/circle for me) the game displays when you mount a boat, it just disappears never to be seen again.

I (PS4) play with a friend (PS5) on a private Realms server and it doesn't look like it happens all the time or at least didn't happen in the beginning. Because it took a while for me to notice until I could actively observe it happening looking down when dismounting. By now I lost several boats because of  this.

He had a few attempts in the beginning when it didn't happen, thinking for a moment, that maybe you need to hold something in your hand (he held a carrot and it didn't disappear), only to discover that it didn't matter and it disappeared on his next try under the same conditions.

We play on the current Playstation version. Pretty sure it says 1.18.1 but were not aware it is a beta.