What version of Acumatica do you have? If you have any earlier than 24R1 then you also must input the customer information into the Avalara portal. For good measure I also always put the customer’s Tax Registration # in the ID field and the Certificate # from Avalara in the Tax Exemption # field. I don’t believe it’s necessary though.
Also, the last integration I did with Avalra the Avalara rep said to leave the Entity Usage Type as Default.
If this happened after an update, I would also check with both your Avalara (submit a case) and Acuamatica reps for help.