I've got one sheet, named External_Data, that contains data that is pulled via a connection. A second sheet references these data with a simple index-match formula, but is returning errors for some reason and I'm losing my mind trying to figure it out. When I point the formula to a different sheet with similar data that is also pulled via a connection, it works just fine. I'm able to go to External_Data and see the value, I can do a quick search for the value and it pops up fine, but the formula just will not work.

The formula in question is:

```
=INDEX(External_Data!J:J,MATCH(B2,External_Data!A:A,0))
```

Column B, a list of serial numbers, is the formula:

```
=IFERROR(Calcs!G:G,"")
```

and External_Data column A is just a list of serial numbers (imported via connection as mentioned above)

Things I've tried:

Changing the contents of column B to be just the value rather than the formula

Changing the lookup value to VALUE(B3)

Changing the lookup value to the actual value

Rebuilding the entirety of External_Data from scratch

Changing the formula to a vlookup (=VLOOKUP(B2,External_Data!A2:J750,10))

I have no idea what's going on with this crap. It SHOULD work. It works elsewhere. It works when I point the formula anywhere else. But for some reason it refuses to cooperate with this particular sheet.