This looks like it may have been a visual bug, it didn't trigger an update to the label of the button, but the upgrade actually happened. (Edit: There was another bug where the Rogue's Den wasn't providing any exp boost anyway, but that's been fixed)
MoratGurgeh is asking what the ratio is if its not 1-1. For example, i had 2 ore and 1 steel which you'd expect would mean they'd each go up by 1 per tick (1 steel = 1 steel per tick, 2 ore minus the 1 steel thats being used = 1 ore per tick). But my ore wasnt increasing in that scenario.
Hi! Thanks a lot for letting me know, I've uploaded a new version (may have to clear cache to get it) which fixes this! Thank you very much :)