I have located the problem and mostly fixed it. There were several files missing from Perforce - somehow they did not get added. However I still have a problem that after I do a build - some of my textures turn "Hot Pink" because they have lost the material reference. "Rebuild all sprites" fixes the issue.
But that does lead to another question. I have two platforms enabled (1x,2x), however when I look in sprite collection's data folder - there are 4 additional folders - I was expecting 2.
For example I have a sprite collection for my title screen name TitleBGSprites.
2DToolkit generated a folder by the name of "TitleBGSprites Data", inside this folder are 4 additional folders; "TitleBGSprites@1x 1 Data", "TitleBGSprites@1x Data", "TitleBGSprites@2x 1 Data" and "TitleBGSprites@2x Data"
Can you explain why there are 4 and what is in each one?