This is the intended behaviour. The default behaviour of all sound modules, when the cursor exits their trigger regions, is to continue playing their content to completion. The behaviour of timelocked single sound modules is an exception to this norm.
If you want to set your multi sound modules to cutoff when their trigger regions are no longer overlapped by the cursor, there are a number of ways to do it.
The easiest is to set the multi sound modules’ playlists to loop. This causes the multi sound module to stop producing output as soon as it is no longer overlapped by the cursor - but it also causes the multi sound module to continue selecting new playlist entries to play while the cursor continues to overlap the trigger region, which may be undesirable in certain cases.
The second way is to apply an AHDSR modulator to the volume of the sound module, and to set its Release and Attack properties to 0. This causes the sound module to immediately fall silent when the cursor exits the trigger region, without changing the behaviour in any other way. This is slightly more work to set up than the first method, but works in a wider variety of circumstances.
Incidentally, the next major version of FMOD Studio will make it much easier to see and set sound module behaviours such as this one.