Sure there will be a direct correlation: SSL decryption requires 100% packets successfully delivered to the AMD, otherwise decryption wouldn't work, by the nature of SSL. Sequence gaps means that some packets are lost on the way, most probably it may be because of overladed switch/NPB interfaces dropping packets or high duplicate packet ratio and duplicates overflowing de-dup buffers on AMD.
Some noise may be present, single-percenates can be expected. Sure 0% is initial, but hardly possible. Fluctuation may indicate some interface overload conditions indeed. It would probably be good to scrutinize with your network team how exactly are the packets obtained from the network, at what interfaces, with what interface utilizations on the way. Look for e.g. 1 Gbps interfaces to which 4x 1Gbps traffic is sent. Or similar misconfigs.
I know you told me already that high sngr would affect the SSL traffic decryption but since it is fluctuating and not always high should we expect the ssl decryption to work when the sngr is low during the fluctuations ?
Unfortunately the answer is - it depends. SSL sessions can be decrypted when they are seen complete from the very beginning, without missing packets, including session establishment . So if you have sessions that start when traffic quality is still good - decryption should work for these sessions. But it's a sideway discussion, really. Without good monitored traffic quality the measurements can't be reliable, garbage in - garbage out:-)