DateTimeDiff returning 0 when comparing same-day timestamps in Architect

Trying to filter out calls that happened within the last 24 hours using a data action, but the expression keeps evaluating to 0.

DateTimeDiff(TimestampFromData, CurrentTimestamp, "Hours") < 24

Both timestamps look identical in the debug log, so why is the diff zero instead of a small positive number? Is there a timezone mismatch I’m missing?