BUG: Intrest not accruing

[PTTG]

I've yet to receive interest on any level... I thought that it was accrued whenever a unit gets killed or something like that, but the guide says it appears at the end of each wave. That definitely doesn't happen.

Or maybe it is... I see... it's at the end of a wave, but not the start of the next one. If it was at the start, then you'd get a clearer idea of how much you earned, and any upgrades you make subtract from your interest.

[The Noid]

Yes, it's at the end of the wave, right after you killed the last creep.
This one has the advantage of being able to use the interest to build more defences before the wave starts... And it makes it a bit harder to sell all your defences before you get interest.