Error: A budget record line with the same combination already exists (even though it doesn't)

I am creating custom budgets in Netsuite (using the ECBV suiteapp).

My current segments are:

Activity (a custom segment)

Departments

Locations

My current budget I am loading has differing accounts, but the same segments. However, I get the following error when inputting the Location into the budget line:

'A budget record line with the same combination already exists.'

I have checked all the other budget records and there is no line with the same combination. I also do not experience this issue with the other segments being repeated in the budget record(department and activity).

I have tried putting in different locations per line, and it works. But the moment I use a location that has been used before (on a different combination of account,department,activity), I get the error message.