Incorrect printline by using different memory segments

At a guess it is running out of heap space.

It might be that you aren't getting exactly the memory assignments you expect.

I don't know how much heap that code needs, but if it is below 16kB I'll eat my hat.

Possibly the code survives over-allocating from the heap because the data cache holds the data for long enough.

FWIW you really don't want to use anything other that 32bit memory (or IO) unless really forced to do so.

Also use tightly coupled memory for all internal memory blocks.