Select an option from the picklist or remove the search term
参照項目にフィルター条件があって一致していないんだと思います。
Unfortunately, I also had this problem but I found a workaround (probably cheating, idk please don't hate me)
I do not have Sean Forbes in my contacts. I tried adding him but I am still receiving the same error message. I also tried what @Otsubo Keiji advised and it somehow worked as it now let me select names on the picklist. However, the same error appears whenever I try to save the case and it returns the error "Value does not exist or does not match filter criteria."
So... I modified one of the contacts' names instead and changed it to Sean Forbes, and I also modified the lookup filter settings. I used the newly modified contact on the case and completed all the required information then I had to clear the lookup filter criteria on the case object manager to let me save it. I did the same for the next case and it finally completed my assessment.
I am not sure if this is a bug or if I missed a module where I need to create Sean Forbes's contact. I'm still stumped because if this is in real life, I basically did not resolve the issue.
Could not find required Filter criteria 'Contact Name: Account ID :: equals :: Field :: Case: Account ID'. Check the instructions..
The issue is, on the Case object "Contact Name" field name doesn't have access to System Administrator profile.