Hello,
unfortunately we were not able to figure out a way to fix my project w/o sending the project to a JMP developer. with my bad project, the developer located one data table in the project that was causing the fault. luckily, it wasn't an important table and we deleted it and then we were able to open the project. one theory about why this one data table was bad was that it had a very long name with some weird characters in it, but this hypothesis was never confirmed. in any case, hopefully the developer responds soon to you and maybe they can get to root cause of why this is happening, it is very scary when you can't open a project where so much of your work is saved!