Highlight corresponding cells where a singular or CSV value in one column matches with a value in another column

[the3rdrock]

Hello,

Please excuse the screenshot in lieu of a mini-sheet. Company security restrictions prevent me from installing the add-on.

I was using a VLOOKUP formula to highlight corresponding cells in columns A and F where a number in the F column matched with an ID number in the A column. This worked.

=VLOOKUP($F6,$A$6:$A$1006,1,FALSE)

I've now changed the spreadsheet in order to allow multiple items in the F column. These are in CSV format, e.g. Row 6.

I've spent two days fighting this challenge, to no avail. The closest that I've come to a fix is:

=ISNUMBER(SEARCH(","&$F6&",",","&$A6&","))

This, for some strange reason, only highlights the blank rows.

Any assistance would be greatly appreciated.

Thank you.