The new DBv3 doesn't like inline comments (--) in the SQL query you must update the query to user multi-line comments to save the queries.
Use This:
/* your SQL STATEMENT COMMENT */
Not This:
--your SQL comment here
Once the comment have been cleaned up you should be able to run your queries again.
Note: if you're using queries configured with rising columns watch the below video on YouTube by the Splunk team.
https://www.youtube.com/watch?v=oPB2Lpd9ZAs
good luck!