Version 4 of MTsort now allows a debugger to be attached to the Event task.
At the point the Scheduler task window says "MTsort processes ready for Use",
or preferably, selecting Pause before each event prior to Going and Resume when the debugger is attached ...
find the running MTsortEvent task...

ps ax | grep MT

Remember the process id (pid) of the MTsortEvent task, for use with the attach subcommand of gdb.

gdb /MIDAS/MTsort/bin_Linux/MTsortEvent
...
(gdb) attach pid
(gdb) directory /home//sortdirs//MTsortEvent.so
(gdb) continue

If the message "Resource Unavailable" appears in the Scheduler window I am afraid you will have to just try again until it works OK.
Not all variables will be visible from the symbol table.

Note: Before exiting the sort progem, make sure the task is detached from gdb ... (gdb) detach (gdb) quit