Can you provide step-by-step instructions that I could follow in order to reproduce your issue? Thanks!
For instance if I search "Soda maker" with all merchants sorting by relevance it says "Showing 1 to 16 of 320 entries (filtered from 2,309 total entries)" and when I change the filter to Low to High it says "Showing 1 to 14 of 14 entries" and then when I change the merchant to amazon it says "Showing 1 to 16 of 76 entries"
Got it. Should be fixed now. The problem was Amazon's back end automatically switching to the "Showing most relevant results" mode in that instance, but I have found a way to override that. Give it another try. Thanks for reporting!