I have had a very similar issue. Friend and I are playing on Bedrock [PC]. We get in the boat together and ride a distance. The other player leaves the boat and they can no longer see me or the boat I am still in. When I exit the boat, the other player can see me but still cannot see the boat. I can see the boat so I can break it and place it back down; only then can the other player see the boat again. While the boat is invisible, it also seems as though when the other player attempts to hit it, it goes unaffected. The boat and other player turning invisible seems to affect the person that was rowing the boat.
Rory Borealis
I have had a very similar issue. Friend and I are playing on Bedrock [PC]. We get in the boat together and ride a distance. The other player leaves the boat and they can no longer see me or the boat I am still in. When I exit the boat, the other player can see me but still cannot see the boat. I can see the boat so I can break it and place it back down; only then can the other player see the boat again. While the boat is invisible, it also seems as though when the other player attempts to hit it, it goes unaffected. The boat and other player turning invisible seems to affect the person that was rowing the boat.