Have you been trying to count the actual number of items selected in a multi-select dropdown range only to run into issues? I've solved the issue for you in this video and demonstrate two scenarios where you can use this solution.
The final count all formula is:
=counta(arrayformula(iferror((split(C6:C10,", ",false)))))
And the final dropdown selection formula is:
=counta(IFERROR(filter(flatten(iferror(split(C6:C10,", ",false))),match(flatten(iferror(split(C6:C10,", ",false))),split(E4,", ",false),0))))
You can replace "C6:C14" in either formula with a column of data in your sheet and this will work for you.
