Hello,
I have two datasets, 1. is a Enterprise Geodatabase Feature Class polygon layer. which is accessed via .sde connection, with read and write access.
the other 2. is a SQL table, which is accessed via a .sde connection, using a sql user with read only access.
I am joining the two datasets based on a common field. Both fields are Text, one is of length 10, the other 4000. An example of the data in each field is, 1. "BAGW01" 2. "BAGW01", they are identical.

As can be seen all items in table 2. match with something from dataset 1.
When the dataset 1 is viewed after this join, all of the fields from table 2 exist but are all NULL. What could be going wrong?
Edit: I've downloaded a local copy of the sql table to my local egdb, and joined that, that works as expected. But this isn't a solution, I need to be able to connect to the live sql data. Just thought id add this as it might give an insight into whats going on.
Edit 2: I've tried to join the table again a few times (after removing joins), now I can't open the polygon layer (dataset 1) at all, I get this error:
