I am using version 1.7. I am also using the Main/Alt addon.

I uploaded my character with the guild information attached. It uploaded my information and sucessfully added and deleted characters in the guild. Everything appears to be working normally.

I went into the Main/Alt screen and looked at the Mainless Alts. I printed them out, went into wow and made corrections to character names in the notes field, promoted some alts who's mains had left, etc. I did a /gp export, and it appeared to export everything nicely. I went to the update page and updated my character and the guild information again. I saw where Main/Alt addon was assigning Mains and alts based on guild information. But the update did not update the notes fields for the characters I changed.

I checked in wow that the changes had been made. I re-exported the information. I re-uploaded it. No change. The Notes are still not updating properly. It did seem to update the guild ranks of the characters I changed though.

Why is it not updating my notes field?

Found the information. It appears that making the note blank causes the update to not update it when the Guild information is updated. I will fix. TY.

You are correct

This was overlooked in the attempt to make roster compliant with mysql 5
It will be fixed in roster 1.7.1