TimestampAdd Error in OBIEE Migration from 11g to 12c

I have a report that works fine in OBIEE 11g but when upgraded to 12.2.1.2, it gives an error stating:

[nQSError: 22025] Function TimestampAdd is called with an incompatible type.

This report has a SQL Expression in a filter that states:

TimestampAdd(SQL_TSI_HOUR, 4.5, CURRENT_DATE)

The problem is that we are trying to add hours onto a date field. When I change CURRENT_DATE to CURRENT_TIMESTAMP, the error goes away.

Final SQL Expression:

TimestampAdd(SQL_TSI_HOUR, 4.5, CURRENT_TIMESTAMP)