Unfortunately, without knowing more about your event, I can’t say for sure what the problem is. However, I strongly suspect it’s that you’re using a mix of timelocked and non-timelocked sound modules.
Modules that aren’t timelocked do not display waveform graphics, and play the sample they contain from the same place when triggered, no matter which part of the trigger region is overlapped by the cursor. This is the default behaviour of modules, as it is useful and appropriate in the widest variety of situations.
Timelocked sound modules are a special category of module recognizable by the waveform graphics displayed on their trigger regions. Under normal circumstances, the part of the sound file played by a timelocked sound module always corresponds to the section of the waveform graphic that the timeline cursor currently overlaps. This special behaviour allows you to do some useful things, such as seek within a sample or suspend the module’s output at sustain points. At the time of writing, only non-looping single sound modules on the timeline can be timelocked.
From the description of your problem, it sounds like you’re placing the timeline cursor in a position where it overlaps a non-timelocked sound module and expecting FMOD Studio to seek within the sample contained within that sound module as if it were timelocked. If you want the behaviour of a timelocked sound module, you will need to use sound modules that are timelocked. Unfortunately, at the time of writing, we have not yet implemented timelocked multi sound modules, so if you want to seek within a piece of music without syncing problems you will have to either avoid using multi sound modules or apply beat quantization to your multi sound modules’ trigger behaviour.