The number of concurrent MultiTrack tasks that can be supported by a controller can depend on the model of controller and the Firmware revision it contains. The documentation for each controller contains a MultiTrack topic that defines its capacity.
Typically the number is 32 concurrent tasks for 8-bit controllers and for 32-bit controllers with firmware issued before 13 June 2014. From 13 June 2014, the number is 64 concurrent tasks.