User-defined LAMBDA functions involving thunks evaluate to #VALUE! errors when saved in .xlsb workbook

Question

I will outline a simple process that demonstrates this issue

1. Create a new workbook
2. Define a LAMBDA function in Name Manager called "thunk" with definition =LAMBDA(x,LAMBDA(x))
3. In A1, enter =thunk(5)(), which as expected will evaluate to 5
4. Save this workbook as an xlsx, xlsm, and xlsb so that there are three versions of the file
5. Reopen each of these workbooks, click into A1 as if to edit the formula, and then hit enter to reevaluate

At least for me, this always results in the xlsb formula evaluating to #VALUE!, while the xlsx and xlsm formulae have no issues. The xlsb formula can be fixed by going into Name Manager and redefining the function, but this is inconvenient. Is this a bug, or is it an unavoidable consequence of the xlsb format? Is it somehow an issue with my version of Excel?

Answer 1

Interesting - this is my version. Strange because it says that I am up to date.

I tested in the April 2024 release and it is not an issue there. I guess this must have been fixed - would be curious to hear if anyone else can replicate in the semi-annual enterprise channel.

Answer 2

OK with all three versions here.