Custom column values showing only for some packets

Newbie with a postdissector LUA script, to extract and consolidate field values from a family (or suite) of related custom protocols. The compiled decoder for the said protocol suite was developed by an unknown developer for WS 1.6.6.

Using the postdissector to consolidate fields from the protocols, to minimize the number of columns required for the Packet List and CSV export file. Also extracted additional (pseudo) fields from the undecoded packet data.

The extracted fields and their values are showing normally in the Packet Details window.

My problem is that only a few of the packets in the Packet List window show the values for the extracted fields which I added as custom columns.

Usually, only one row will show extracted values for every page of the Packet List.

If I add a column from the suite protocol decoder, the corresponding LUA extracted column will then have all the values shown.

Please kindly advice possible causes of and ways to resolve this problem.

TIA.