Can confirm, it stops dealing damage after a set time, its not random. This only happens when attacking the same target over a set time(~30s). If the tower switches targets it resets the set time and bug doesn't happen. I also want to point out that flame towers do not attack flying targets.

Still not fully fixed. If Flamethrower is built near spawn point it sometimes tries to attack some enemy inside the spawn area and then freezes until the enemy gets out of spawn. Problem is, if it's a book or javelin thrower it may take some time or happen never if there are barricades next to the spawn that can be attacked.

I can provide a video which shows the bug :>

Flamethrower stops dealing damage to the current enemy the moment you use an ability.

Easily reproduced in Tavern - simply have Flamethrower target a dummy then use Manabomb away from the target. The DPS will stop but the flame will continue.

Edit to the above:

Flamethrower will stop doing damage if you use manabomb. Easily reproduced by testing against dummies. However, the moment you switch to another character or upgrade the tower, it works again. UNLESS YOU GO BACK TO Apprentice then it stops again!

It may stop attacking if u use manabomb - but i afk'd the whole wave and some mobs were still hitting my trees. Both of em ( flamethrower and Nimbus) havent done anything. The flamethrower was fireing and the nimbus just stood in the air chilling.

Here are some more screenshots showing the bug:

There is more to it than FFT's not attacking. There's also a bug that, even when attacking, no damage is being done.

This problem SEEMS to occur far more frequently the higher the FFS's range gets.

<video controls="controls" width="300" height="150"> </video>

Testing whether video works:

<video controls="controls" width="800" height="150"> </video>

yea it stops attacking sometime

As said above using Manabomb stops Flamethrowers from dealing damage. But also using it again and or killing their target makes them deal damage again.