It doesn't only happen if you enter the giant goddess map; if you leave the starting map (Ironia), all non-recruited companions will disappear (this includes going to mossy expanse and going to the arena inside monsters).After updating:
-if you enter the giant goddess map before recruiting a companion they will always disappear
-what negro said about armor
-game still crashes about every 10 minutes
-Werewolf quest now works
-existing monsters town into the main map sometimes plays both of their music at the same time
I don't wanna make an itch account so I'm just posting for anyone downloading it
Also, the issue with music might be from loading a save while you're in a scene. (This has been a bug that i've been experiencing for a long time). You can avoid triggering it by exiting to the main menu and then loading back in from there. Unfortunately, if you do trigger this bug, the only way to get the music to go back to normal is by quitting and relaunching the game (in my experience).