StartIsBack does not change bluetooth icon design (StartAllBack does). Bluetooth icon may come from different stack. Built-in one is pretty much useless anyway
There are some reports on this, but no proper reproduction, so it's not going to be fixed. If you can arrange remote access to system with proper reproduction, please write to startisback@gmail.com
I'm sorry, I don't think it ever worked 100% well in any Windows version.
Please test an interim build with weather on the left http://startisback.com/StartAllBack_setup.exe