Import of files from disk fails after a few thousand frames

I am using iStopMotion to make a time-lapse movie from images from my Hero GoPro 3 Silver.
Using the Import menu (and using drag&drop), I can import 3031 frames before getting a “Reading File Failed” error. The file size of the movie is 4.71 GB. I have tried importing two ways:

  1. 999 pictures at a time starting from the beginning of the time-lapse and then adding to the end of the movie
  2. 999 pictures at a time starting from the end of the time-lapse and then adding to the beginning of the movie
    Both times I get the error and a file sized 4.71 GB.

Is there a maximum limit to the number of frames or file size of a project?

(There is 26.01 GB free space on the drive.)

Unfortunately this limit comes from MacOS-X. We are allowed to handle a certain amount of files per running session only. So you should close your project, restart iStopMotion, reopen the project and add the next bulk. Sorry for the inconvenience!

The inconvenience is a small price to pay for a work-around that will allow me to accomplish my task.
I had closed the project, but not the program itself. Now that I know what the constraint is, the solution makes sense.
Thanks for the quick help!
Exceptional support!