iTunes song Grouping category goes blank

I have been spending a fair amount of time filling in the "Grouping" category, found in iTunes songs, when I choose Get Info. Sometimes I will select several songs at once, and Get Info, to add other info, such as Album Name, Artist, Genre, etc.

When I do this, does it wipe out all other customized data for those songs? I just checked several songs that I had added data to Grouping, and found that they are blank!

Let's see if I am understanding your question correctly. First you enter some specific information about a few songs such as song title, comments, etc. Then, you select a group of songs (including the ones you entered custom information for) and enter general information for the group of songs (album title for example).

I've done this before and iTunes usually does not overwrite the custom information unless you enter something in one of those fields. If you enter an album title in one or two songs for example, then select those songs as part of the group the album info will change only if you change the information for the group. Whatever you enter last takes precedence.

Grouping field is blank

Yes, that is what I am doing.

It does seem like iTunes should not wipe out my Grouping data that I entered, but it has been wiped from most of the songs I entered data for.

So aggravating.