I have 2 stage 3 boxes from FF and they are awesome. FF is a reputable company and if they screwed something up they will own it that said it sounds to me like you have some other issues going on, not saying the box is good but in order for things to work everything must be good.
Do you have aftermarket parts in the front suspension? Altered ride height? Dropped spindles? Was the alignment done correctly? Do you have a print out of the settings?
Something is going on With this car and I don’t fault the firm feel box automatically. I would think that box is a good part and the other parts around it are at fault.
I also have 2 Firm Feel stage 2 boxes and I am very happy with them. As others have said, I think you need to look for other issues like debris, alignment, installation, etc.
Yes, there could be an issue with the box, but it sounds more likely that there are other issues going on.
Good luck and I hope you find and resolve the issue.