Bad password when my friend go to cave

Hi Developer, 

This issue was happened after Dec update, before i have a one year save and it didn't have any issue when go to the cave. 
After the update, when my friend go to the cave, she will got a error "Bad password " actually i didn't set any password for the server and it is a friend only server. 
We were so sad and she cannot get into the game any more (as she last position was in cave). 
So we decide to create a new save and its everything was fine (even go to the cave). But unfortunately, after few days and when we want to the cave during the summer, the bad password issue happened again. anything i provided can solve the issue? or whats else i can do on it ? 

Here the summary 
1. After dec update, my friend (not the server holder) can not go to cave and will have "bad password" error even the server didn't set password 
2. New world, first time my friend (not the server holder) can go to cave and everything normal. Along the game progress, when she try again, the "bad password" happened again 

Remarks 
Server: Mac Mini M1 
Joiner: Window OS
Platfrom: Steam 

Regards, 
Godfrey