CIS-Navy & Akula transmission

My friend Mario often monitors the frequency of 9201.0 KHz/USB in search of "Akula" signals: he mainly uses a KiwiSDR receiver located in Japan (Azumino-city, Nagano) [1] and it seems that this frequency (certainly one of the many) is quite active for this kind of transmissions, as collected by my friend Dave too. Most of the time it is usually a pair of signals that repeat at irregular intervals.
A few days ago he kindly sent me an interesting and "curious" recording of a transmission in which both an FSK 50Bd/1000 signal and Akula (FSK 500Bd/1000) are used with a central frequency of 9202 KHz (Figs. 1,2) 

Fig. 1

Fig. 2

The first thing that catches the eye is the particular "shape" of the Akula signals in which the well-known initial synchronization and preamble groups are missing but the EOM + EOT groups (101111 100010 100010 101111 011110) are exactly in their place, as can be seen from the demodulated bitstream in Figure 3. Just one year ago I had already come across these (let's call them) "anomalies" [2]. "It could depend on a malfunction of the modem or on the receiver's attack time" my friend cryptomaster says.

Fig. 3 - Akula bitstream