I have experienced it today too.
When I searched dust for anything i get the dust for gems displayed, if I am on the first page (1/4) and search dust for gems i get the avaibale offers displayed too, but if i change the search from dust for any to dust for gems when I'm on page 2/4, 3/4, or 4/4 i get displayed nothing.
Edit:
Did some further testing: For silk for crystals i have 2,x pages of offers out of 4 total pages of silk offers. There the bug only occurs when I change to silk for crystal when I'm on page 4/4.
Steel for planks is even more wierd: I have 1 page and 2 offers for it in the trader when I change to steel for planks on page 1 and 2/3 everyhing is fine, but when i change to it from page 3 i get on an empty page 2, even if there should be 2 offers... page 1 is normal.
When I sort my trader for scrolls for crystal i have 6 pages of trades, if i change the search to steel for crystal when I'm on page 2+ i get an empty page, even if there are 6 offers for steel for crystal.