Can you give me an opinion on this issue ?
I have two :
- Keep calm when possible
- Try to get help from FileMaker Support and in particular to see if yes or no all is to rebuilt : Maybe they will accept to receive and analyze a clone of your database
More generally, you will not find any system in the world that prevent all type of corruption, since it can be due to a hardware failure.
Did you try a Recover ?
You may also find a third party product: FMDiff to be a useful way to check your file for damage.
I'm chiming in because right now I'm facing the same issue and after 25 years working with FileMaker I'm seriously considering moving to another platform in a year or two at most.
It's just ridiculous we can't see the CSS of a custom theme. In my case I have something with a corrupted font, that breaks all objects when I paste them. My current workaround is to change the font of the object group, paste and then change the font back. Why not we can open the Theme CSS, check what's wrong and fix it?. I can't even analyze the DDR without modifying the XML first.
These are the kind of issues that makes me hate FileMaker from time to time. I regularly love the platform but some days is harder to keep the faith.
Just a last minute note, I made a recovery and FOR NOW, it is working...
You're not the only one in the rebuild-the-layout business. Have had that last year and there was no means of finding out what was wrong or fixing it. (FMP 14.0.2 OS X 10.10.5)