I think I've found another bug.
To get a minimum test case. I have a sharepoint list called Test with a Title (of course) and an text field "SN".
ClearCollect(
Test2,
RenameColumns(
Test,
"SN",
"OrigSN"
)
);
ClearCollect(
Test3,
AddColumns(
Test2,
"SN",
If(IsBlank(OrigSN),"",OrigSN)
)
)
This should work, but adding an "SN" column to Test2 fails. If I call it "SN2" it works fine. This doesn't seem to be an issue when the orginal source is a local collection, but it is an issue when it's a sharepoint list.