If you see this warning message and the tachograph is not downloaded for many days:

Then you should right click the terminal in the Vehicles list and select "Download current tachograph"

Enter the download from day as show in your case in the logs and the download to date to the previous date that can't be downloaded so in our case from 2020-06-30 to 2020-07-24

Then you will be able to download at least the data that can be downloaded from the tachograph.

If you see an activity error on the last day of the download. Then you should take the truck into a workshop for inspection because the tachograph is probably damaged.

You can try to make download with the download day interval option after the damaged date if there is some other good data that can be read out from the tachograph.