Tachomaster is missing some days that I worked. This is week 5 on Livingston to cairnryan trunks which have been Monday to Friday with 2 Sundays. 4 random and inconsecutive days are missing. Why would this happen?
I use Tachomaster and I’ve never had this happen, I’d say it’s almost certainly a temporary glitch on their website although you could do the download again and see if that fills in the blanks. 
It gets downloaded at the end of every shift and knowing they pay from it, my tacho shows start to finish. I always manual entry the end of my last shift and start of new shift. I just printed off all the missing shifts from my new contract (week 5 now) and there must be around 14 shifts missing in that period. Some random, some are consecutive. This may explain why my weekly average has dropped 2 hours in 5 weeks when I am averaging 65 hours a week duty time 
If you are not set up as a full time driver, or if you were in a hired motor then you will not be on there.
Right click the date on calendar view
Click “Expecting Data”
Refresh or re-download card
apart from 2 shifts which were both older fleet vehicles, i only drive 63 plate DAFs which are fleet vehicles. i dont touch the hired trucks as this is a separate contract. we dont even fuel up on the same site as the trucks are kept