I think posting your XML would be helpful because I'm not sure where you're getting the error.
Here is a stripped down basic example of a dropdown with 4 options, which are used to drive the output of a SQL query against an Oracle database named "mydb". Try this out on your system and see if helps
pulldown_time_range
Time Range (Hours):
Last Hour
1
Last Day
24
Last Week
168
Last Month
744
| dbquery mydb "select to_char(sysdate, 'YYYY-MM-DD HH24:MI:SS') current_ts, $pulldown_time_range$ pulldown_time_range_hours, to_char(sysdate-($pulldown_time_range$/24), 'YYYY-MM-DD HH24:MI:SS') pulldown_ts from dual"
false
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