Issue
We were unable to upload files larger than 5MB (as per the rule set in DocAve 6.0 console) in a SharePoint site for an RBS enabled farm.
Analysis and solution
As you know, DocAve created Stub database for each Web Application.
Hence, what happened is that this Stub database for the Web Application was renamed after the execution of the MoveStub (to move site collection) command for which we can not open the files.
Normally, it should rename the database back to its original state after successful execution of this command, but it did not happen in our case.
Thus, we have to manually rename the database name to the actual name with the help of our SQL team, then documents started opening without any issue.
Also, there are few WFE Servers, where we were still unable to upload the files. To fix it, you may need to restart the DocAve Agent Service (in services.msc) in the respective WFE Servers.
I hope it helps.