I use MP3Tag to re-name the 'Album Artist' for each song to that of the Album name. It seems to work for me. Also be careful of how your media is numbered. Try removing numbers from the beginning of the file name in case it gets confused.
from Kodi Wiki:
7.1 Artist Tags - Resolving Compilations and Multiple Artists
Kodi reads the Album Artist tag in ID3, Ogg, APE and MP4 tags and uses it if available to assign an artist to the album (independently of the track's artist information). This is the "Album Artist" tag (in ID3 this is represented by the "TPE2" tag; in vorbiscomment (ogg) files "ALBUMARTIST", "ALBUM ARTIST" and "ENSEMBLE" are all supported). Multiple artists for either a track or album artist can be specified in "Artist1 / Artist2 / Artist3" format.
If no Album Artist tag exists, Kodi will use the first (primary) artist from the tracks as the Album Artist. Essentially we do a string comparison of all the track artists, and assign the common artists as the Album artist. This is generally the TPE1 tag in ID3.
As many users don't yet use the Album Artist tag, Kodi has an additional filter system for identifying compilation albums, where each track normally has a different artist. As Kodi scans a folder, it does the following:
Identifies albums based on Album name alone in the folder and groups the songs that have the same Album name together as an album.
Runs through each album's assigned songs. If there is 2 or more tracks with the same Track number, the group of songs must come from 2 or more albums, so the Album name is ruled out as a possible compilation.
If any of the songs assigned to the Album name have an Album Artist tag, then Kodi assumes the user knows what they're doing, and this album is also ruled out from being a compilation.
If two or more songs assigned to the Album name then have different primary artists, then the Album name is considered to be a group of songs from a compilation, and the Various Artists" tag is assigned as the album artist.
Otherwise, if all the songs have the same primary artist but don't have the same full artist list (eg a song or two has an additional artist) then the album is assigned the primary artist as it's Album Artist, and we assume the additional artists are guest artists.
