iTunes is not grouping songs by the same artist together.

Steve MacGuire a.k.a. turingtest2 - iTunes & iPod Hints & Tips - Grouping Tracks Into Albums - http://www.samsoft.org.uk/iTunes/grouping.asp (older post on Apple Discussions http://discussions.apple.com/thread/2099465?answerId=9910895022#9910895022)

Quick answer: Select all the tracks on the album, File > get info (or right-click > get info > details), and either give them all a single "album artist", or check the "compilation" flag (as in https://discussions.apple.com/thread/3756735?answerId=17670085022#17670085022).

If these are from multiple-CD sets you may also need to enter the appropriate information in the disc number fields. If they are not a multiple CD set you still need to make sure the disc number fields are set correctly or all empty.

Another explanation by hhgttg27 August 2015 - https://discussions.apple.com/thread/6864334?answerId=27784417022#27784417022

If they still really do not want to group check this Aug. 2008 post by turingtest2 about temporarily changing labels - https://discussions.apple.com/thread/1670662?answerId=7904806022#7904806022 or http://www.samsoft.org.uk/iTunes/merge.asp - This often works but I have had cases where tracks grouped when a letter was added but ungrouped when it was removed again.

If they are mp3 files try changing the ID3 tag version which may cause iTunes to re-write the tags and clear up inconsistencies. I use iTunes 7.5 (yes, from 2007) so I can't tell you where this is in later versions.

I had one case of really stubborn grouping. The tracks would re-group in ways that didn't make sense when I changed metadata. Without going into detail, I deleted the tracks completely from iTunes, then re-added the files and they all grouped correctly.

Limnos thank you so much for linking those threads - the solution provided by Turingtest - adding an 'x' and then deleting it again - worked for me!