Managed to solve “Cannot dehydrate” error. Not sure why it happens, but I got a pointer on when it happens via this post (Why are Google API keys required? - #7 by shot).
Basically it happens if you select the marker data type as geographical address and put the list of geographical addresses in the source. I was having a custom state with a list of addresses. I changed it to a field in a new data entity in the db. And then gave the data type as the entity instead of geographical address. This solved it.
However, of course this is still a bug. Don’t know whether it is at Bubble’s end or at plugin’s end.
And other issues remain.