I use LimeSuite.dll the header file LimeSuite.h and the API document "LMS API - Quick start guide". This was working 100% with the codebase from September 26th, 2016. The new firmware / LimeSuite.dll has introduced the problems.
HF tuning did work, although the filters in the V1.2s boards made it hard to use - marty posted some screenshots / videos.
The situation with the images - this you can test and reproduce with the LimeSDR-USB Quick Test program. Try 5MHz with the FM Stereo band, see the signals, compare to the same spectrum with a 10MHz bandwidth.
I've changed nothing in my code since September 2016 other than compiling and linking against the latest github code.
I'm happy to talk on SKYPE, you can use my software to see the images - compare these with FFT Viewer.