Search comes up empty when filtering by reference_id

Here is my search:

curl \
  -X POST \
  -H 'Square-Version: 2021-03-17' \
  -H 'Authorization: Bearer xxxxxxxxxxxxxxx' \
  -H 'Content-Type: application/json' \
  -d '{
    "limit": 1,
    "query": {
      "filter": {
        "reference_id": {
          "exact": "276"

When I search by email it pulls up the account but I can’t seem to pull it up by the reference_id, am I missing something with my search request?

I’m trying to search for existing customers first so that I don’t create duplicate customers in the database, but unless I can reliably search for the customers based on the reference_id then I have no choice but to blindly create a new customer for each new order, which in many cases will result in duplicate entry for a given customer.

I guess I can search based on email, since that seems to work. However there is still a potential for duplicate customer accounts if I filter by email, but something is certainly better than nothing.

I was searching the sandbox instead of my actual customer list.