Microsoft released a bad version of the Minecraft Bedrock server. The bug can be tracked here: https://bugs.mojang.com/browse/MCPE-239705
As of 6/27/26 this is still an issue. You can try toggling the “LAN Visibility” setting in AMP (search in the top right of the instance) and see if that resolves it. Otherwise, you must wait for Microsoft to release a fix.