Carpet square issues

[Bccc]

Good evening, i have been cleaning a commercial building for 6 years and just last year they ripped out the old carpet and put in carpet squares. I went to clean it the other day with my cimex and DS and i am having a hard time removing some spots that were easy to remove with the old carpet. I have gone back and lightly sprayed them and used a towel to get them out but i am still having a hard time. Anyone else have any ideas for these squares??