

Trying to identify the source of the noise via soloing and such was inconclusive, it doesn't show in any output / mixer track and deleting the entire rack of instrument didn't make it stop. Always care for your ears, as tinnitus is dreadful.

I'd also say, be watchful massive high pitched noises from nowhere, it can damage your hearing. Make sure no INcoming signals are going to mixer tracks, or possibly saved on Mixer Track presets you may be loading in. When it occurs, find the sources using soloing techniques, replace it with a random similar instrument, of the noise still occurs it could be a routing issue. How are you identifying it as Cinepiano? Is it being identified through the plugin track flickering on solo, or is it coming from the mixer channel? If you reopen it and it is there, then something is occurring mid project to produce this. If you open it, and it's no longer there, it's FL or the Plugin/library is malfunctioning. When it occurs, saving as a new project, then reopening it would help determine if it's an FL studio problem or a plugin which eventually malfunctions or it is something which is occurring as part of the project. I guess another troubleshooting question is: Google gave me no probant results about FL nor CinePiano, and the library is currently unusable for me as I don't want to dread having my eardrums punctured every time I stop my playback… I would be grateful for people manifesting if they encountered something similar. I can't formally prove it, but it occured only in projects where I used this library and replacing the instrument with another piano was a successful solution so far. The issue seems to have something to do with CinePiano. For some reason it shows up in the audio indicator bar at the top of FL's GUI, but the master track of the mixer doesn't pick it up. It's a simple waveform but, and I can't stress this enough, sufficiently loud to be absolutely fucking ear-piercing. Occasionally, when stoping the playback, FL Studio will suddenly output an extremely loud sound, that will not stop unless I close the software or shut down my audio device. I've been dealing with an very annoying issue for some time.
