I am hunting for a hidden ability feebas, and i am using a ralts with trace to check the abilities, but at the start of a battle ,at least while fishing, i get no prompt or message about what ability was traced it is not until after i switch it in and out again does it say anything.

This is a duplicate of https://pixelmonmod.com/tracker.php?p=2&t=15762. Also mentioning here as I did there that it's not just Trace, it seems like all abilities that announce when the Pokémon is brought in aren't being announced at the start of battle. They do seem to work though, and they will announce if you switch the Pokémon with the ability in, rather than leading it, so that can be a workaround for your Feebas hunt until the issue is sorted.

Thank you for the report. However, this ticket is a duplicate.
Link to original ticket: https://pixelmonmod.com/tracker.php?p=2&t=15762