Of course the development is active. It is open-source and you can check the coding activity in GitHub: https://github.com/NebulousLabs/Sia/pulse In the last 7 days, 7 pull requests were merged, 4 were opened and 11 issues were closed.
The Release Candidate 2 of the future version 1.3.2 was released to beta testers this week. Most probably the general release of 1.3.2 will take place in 1-2 weeks. The biggest features of this release are a huge revamp in the file downloads speed and reliability, cheaper contract formation fees and scalability for the wallet, so exchanges don't have more issues in the future (Poloniex issues should be solved as soon as they apply the update).