Hey there!
I'm Lorenzo, Italian 23-year-old graphic designer and novice type designer. This is my first message in this beautiful and high quality community and... unfortunately I have a problem

I'm working till a month on my first typeface.
In these days, in particular, I'm working on the kerning.
I created all the classes (inspired by what other type designers did), and THEN worked on the kerning.
The kern opentype feature was fine, no problem.
Then I made the mistake to open with FontLab the .otf file instead than the .vfb. I edited some kerning pairs and save the file before I understood that was the wrong file.
Too late.
The new .vfb file has some problems in the kern feature: the pairs are no longer grouped inside the kerning classes I created!
Could you please help me on how to reverse this? Or what I have to do to put back things in order?
Thank you very much guys!
Lorenzo.
Here some screenshot:

Comments
I left here the solution in case someone in the future have the same issue.
First go to Kerning Assistance (Tools>Kerning Assistance) and click "Compress".
Then, open again the Kerning Assistance Window and generate a new kern feature.
This will solve the problem