For several reasons epoxy can go bad. Damp climate, mixing wrong proportions of the glue. Most systems aren't freez thaw stable. I use the West Systme Epoxy mix. It is a bit pricey but it's great stuff. Thanks Dave

 

Yes hardner can go bad. But at what temps are you spraying that epoxy in and how long are you keeping that epoxy in those temps? Epoxy likes nice warm temps, it starts to shut down at around 60 degrees. Below 60 it wont cure

 

I was spraying in my shop where it was in the high 70's. I applied the coats fairly heavy, but I allowed about a 10 minute flash time between coats, I though I might have applied too much at once maybe. I even payed close attention on mixing to make sure I mixed 1:1 just like they said to. Which way would be most likely to screw the mixing procedure up,too much epoxy or too much activator?

 

IMHO, I wouldnt be worried about epoxy being tacky or soft after just 3 hours. Some of the epoxies I've used have been soft for up to 12 hours. Since filler can be applied over epoxies up to 24 hours (depending on brand), it makes sense to me that it doesnt fully cure right away.

I was worried about this same problem when I first started using epoxy, but after about 24-30 hours, the stuff was tough as nails. If it's still tacky today, I would agree that there was a problem with the activator.

 

I applied the coats fairly heavy, but I allowed about a 10 minute flash time between coats

Heres probably your MAIN problem!!!
All you need a med WET followed by atleast a 30 min flash time. Two wet coats will get the best protection, any more wont gain you anything.
Epoxy is a slow curing product in the first place and you piled on the epoxy. You just trapped in the solvents not allowing them to properly flash off or escape. Now the surface is tacky