Here ya go!
Bad Request (400) Errors
This is a cache/cookies related issue.
I am forwarding this bug to the developer.
I have seen this happen on a few different sites (not many) and it seems to be having issues with some specific browsers and the new GDPR integrations they are using with our platform. I read the changes are not 100% compatible yet. This is effecting auctions when someone else beats you to the sale and the cache is still showing them as available to you.
They should work themselves out when the platform updates.
Right now, the best thing to do is to clear your cache and cookies. Not with a plugin or extension, but the old-fashioned way using the instructions in the link above (following the instructions fully).