Why does the AR transaction DFF parameter BatchSourceSeqId not work to derive a default DFF value?

Summary:

Purpose is to default a value coming from the AR transaction source DFF segment onto a transaction header DFF segment.

Therefore created a transaction header DFF segment with following initial default (default type SQL):

select rbs.attribute1
from ra_batch_sources_all rbs
where rbs.BATCH_SOURCE_SEQ_ID = :{PARAMETER.BatchSourceSeqId}

This does not work. However this works:

select rbs.attribute1
from ra_batch_sources_all rbs
where rbs.BATCH_SOURCE_SEQ_ID = 300000008856183

So the parameter does not return the source id. Why not?

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