random ODBC error DAY INF LAG NAN NOT RID ROW RRN CASE CAST CHAR DATE

Hello,

My report had been running without problem but recently, after hitting the refresh button, I keep getting error message below: 

ODBC: ERROR [42000] [IBM][System i Access ODBC Driver][DB2 for i5/OS]SQL0104 - Token  was not valid. Valid tokens: ( + - ? : DAY INF LAG NAN NOT RID ROW RRN CASE CAST CHAR DATE.

and it is random. I could refresh the data successfully in like every 2 or 3 attempts.

I already tried re-entering the username and password to the DB, it worded for half day and now I still get the error messages...

I've seen people saying merging external and internal (already in the query editor) data source could cause problem but the two tables I have are all internal for the merged table that has the problem.

My Power BI is also up to date. (Feb 2022 version)

Any ideas how to fix this? 

Thanks

Jessie