We are testing writing to an SD card using the TWR-K60F120M board, running MQX4.1, with the HVAC demo and SD driver and MFS library included. We can open a file and read from it, then open two more files in write mode, but it will only work with the first file that is written to. Upon trying to write to the second file the task is blocked. This is the same whether I use fprintf(), or write(). The file handles are not NULL, and it doesn't block when the files are open, only when written to some time later. I doubled the stack size (to 10kB) and it didn't help.
Is there a limitation with accessing multiple files through MQX MFS, or are we doing something wrong?