Power query filter rows by contains text

Hi,

Simple table with added custom ;

 Table.AddColumn(Custom1, "Custom", each Text.Contains( [Column1], "a" )
or Text.Contains([Column1] , "t") )

Not sure if this is best way but it does give a correct result , if there better ways involving List.ContainsAny etc please let me know.

But what i was trying to do was filter by these true /false so;

 Table.SelectRows(  Custom1, each Text.Contains( [Column1], "a" ) or Text.Contains([Column1] , "t") )

this returns only one row that is correct and an extra, not sure why the above does not like 't' when changed to 'x" it works but still xtra row?

Any help?

Book attached with attempts including Textpositionof .

Richard.