As this was recognised as a bug and deemed fixed I would log an SR providing a detailed test case, this should give you leverage to get a rapid resolution.
If your question is answered could you kindly close it / mark correct / helpful as appropriate.
Have you seen the presentation services log? please, as initial point to see the root of cause of the issue we need to check it, as a second check the obiee server logs, and is not probably the key factor of the issue but , please, can you check in the web browser certification matrix ?
Also the SR clearly states "Fixed in 12.2.1.2" and you talk about.... "12c" which is about as unprecise as possible since at the moment there are 19 (nineteen!) different "12c" version as you can see from MOS Doc ID 2070465.1