When you shift-click items into the chemical dissolver, most of the outputs are voided. But sometimes there is some random output like Aluminium Oxide when packing in Gravel or stuff.

Yes, some blocks have a random chance of outputting aluminum oxide as indicated by JEI. Could you please be more specific on how exactly I can replicate the 'problem'?

And i'm a total idiot, clicked on the wrong block to look into the drop rate. Sorry for wasting your time -.-