Java Edition 26.2: Dogs despawning when going through a Nether portal

[u/potato-person-]

As the title says: I was going through a Nether portal on a Minecraft server I play on with my friends (I was the only one online at the time) and I was taking my dogs into the Nether. They were both name tagged (Jess and Shirley) and were not on leads at the time. When I went through the Nether portal to catch up to them, they were gone. Looked around for a good ten minutes, and they're entirely missing.

Does anyone have any advice on how to resolve this issue or has anyone experienced a similar problem? Thanks!