I got the same exact problem too. Most of the https sites work, but Facebook, Twitter, Google and etc. don't. My OpenWrt is 18.06.2. shadowsocks-libev-ss-tunnel - 3.1.3-3.
But if I don't use the transparent proxy ss-redir and use ss-local, all these sites work. I suspect it's due to the DNS pollution problem, and something is over-writing the ss-tunnel.