I have run into the same trouble on our site (www.ccofpl.org/signup).
I hit the wall at 141 tasks and it will not take any more. I hit the save button when I add and it opens the new page.
While at 141, if I hit the save button, it says “saved Tasks successfully”, but when I add 1 more task, the save does not work and opens the new signup page.
I have tried copying it to another one and the new one has the same problem.
This appears to be something on the plug in. I just updated it today to 1.12.1 and that did not help either.