I just saw an announcement from Microsoft that all users must upgrade to the latest version by March 1st, or no longer be able to use the Skype services (see blog post).
This probably is related to the change in Skype's network architecture. Microsoft has been transitioning Skype away from its old peer-to-peer network architecture to a modern server based architecture for performance and scalability reasons. Under the old architecture, the network consisted of three types of entities: supernodes, ordinary nodes, and the login server. A supernode was selected by the network based on its internet connectivity, uptime and whether it was running the latest version of the P2P code. Supernodes were responsible for maintaining the index of peers and well as handling NAT and firewall duties for other peers. Under this architecture, calls were not routed through any designated servers. Instead, calls were established directly between participating Skype nodes (clients). As a result, the old architecture made fulfilling any government request for "wire" tapping allegedly impossible (see ZDNet article).
The old architecture probably explains why call information never synchronized between my different devices.
P.S. Did you notice the TM on the Skype logo? Back in May 2015, British broadcaster Sky successfully blocked Skype from registering its logo on the grounds on likelihood of confusion with its Sky mark (see General Court of the EU Judgment).