CO2 bug??? I didn't mention any problems with CO2 levels...
It was a compressed air problem. (in fact,this is the first time I've ever encountered a compressed air supply issue) Compressed air dropped to 25 % and would not replenish....even though the compressor was not damaged....not even after the boat was surfaced. You see when a submarine is surfaced, that is the time to refill the compression tanks as no or very little compressed air is being used on the surface and unlimited air supply is available for compressing.
As far as shore batteies , nets, random mines...these could not be the problem in the open sea, far from any land mass.
It wasn't a saved game problem either. Even though I did a couple of saves as I always do for a saftey margin...this patrol was definitely a one gaming session patrol. No saves reloaded. Plus too ,as pointed out damage can be reloaded but I would have to assume that repaired damage is equally reloaded as repaired damage.
If this had been a one time event It could be easily dismissed. since it happened twice and led to unexplainable consequences...it becomes another matter. How can one defend against a danger that can't be defined?
I'm playing patrol 14 today. If the problem does not repeat itself then my hunch of a 13th patrol jinx encoded in the gameplay is as good as any. If it does them a deeper investigation is in order I would say.