Sparkline not showing gaps


We have a project that has sparklines inside tiles on a display page.
The existing system is on 7.9 so we set up a tag and history provider to read the same tags in 8.0
When the comms drops out from the site there are gaps in the sparkline in 7.9 but 8.0 doesn’t show these.
Instead it displays as if it reads 0.
See images below.
All settings on the sparklines are the same. Is it a setting on the gateway that needs changed?

image image