can't open my project anymore

since yesterday, I can’t open my project on iPhone and iPad anymore.
My project is on Dropbox, but if I try to open in inside the scrivener app, I get the notice: “Checksums not found, please sync again”. That’s the same on iPhone and iPad. I tried to sync again several times, but the problem stays the same. Is there anything I can do to get my project back?

Does the project open okay on your Mac?

Yes, indeed. I opened the project on the Mac and closed it again. After that, I was able to open the project on my iOS devices and everything seems to be fine now. Thanks a lot.