Just now got an answer from ebay support:

"Thanks for contacting eBay about the error you encountered when searching an item within a specific location.

We apologise for any inconvenience this error has caused you. We are fully aware of the situation. We have received the similar reports from other members who are also trying to search items by filtering it by location. This has already been reported to our Technical Team and they are still on the process of fixing this error.

I appreciate your patience on this matter. Have a nice day!

Regards,
Azabelle L. 
eBay Customer Support"