There's no error showing. Please see print screen. As soon as I enter any number above 1000000 in the MAX or MIN fields it goes automatically to 1000000 and flashes 3 times in red. So I can't search for any product id because they all start above 1000000
By the way, I have one different store and this is working fine in that store. So in the first one (with the error) I come from old PS and have been migrating. In the second one that is working fine, I have just migrated once from 1.7 to 8.1...so I guess there is something to do with the migration from 1.6...