[BetterRed]

@AnneT - AV products, perhaps more than any other class of software, are subject to very frequent updates because the AV developers are forever playing catch-up with the bad guys - bit like cops chasing robbers. And, most AV products update silently, those that don't update silently are very annoying, when they seek attention every day or two.

So, whilst you may have been using Bitdefender for 2 years, its 2018 codebase is almost certainly not the same as the 2016 codebase. Bitdefender developers might have introduced a feature to block programs that access the 'net repeatedly - perhaps as part of their anti-ransomware strategy.

Most AV products have a facility to exclude paths from their purview, try excluding the calibre2 directory.

BR