This showed up on the list of glitches. My suggestion is to keep screenshots for your state if you must, and start over if it doesn't pick up.
Even more important, contact an existing school within your state if they haven't extended their deadline and see if they received an ISIR from you. Ask if they can help you document it because you have a known error and that it deleted your application. They may direct you to the FAFSA helpline, or the state navigators.
Same happened here. Daughter tried to add a school and it’s gone. I called one of the schools that hasn’t sent an official award letter yet and they were able to see the original application so hoping all is not lost
Same. Mine is gone from all accounts.