Same problem here, and starting around the same time after updating to v1.20.
Slightly confusing because I was also implementing all the consent stuff which necessitated the upgrade to v1.20.
Anyway, as well as no purchase event, I have no ecommerce object on the order received page . There is the orderData object which I guess is what Woocommerce generates. But no ecommerce object and therefore no info in the datalayer.
Do others also have this additional and probably related issue?