Enhanced Ecommerce not tracking on 1 of 3 sites

Our client is a small retailer with 3 locations. Each location was an existing business that we purchased over time and added to the company, so each location has its own website and GA account.

We're running a multisite Magento 2.3 installation for them, with the WeltPixel GA Enhanced Ecommerce extension.

For two sites, the ecommerce tracking is functioning as it should. Transactions, product data, order values, etc., are all coming through.

For the third site, there is zero ecommerce data.

I've tried reviewing the settings, our PPC team reviewed the setup, our developer reviewed things ... we're all stumped.

Any suggestions from the community on what to look for? Has anyone run into this issue before?

Thanks!