I am having a lot of issues when running Jet Reports - I am writing the report and everything looks okay but once run they look like this:

But the rows are running - when i drilldown the values appear

I am running the latest version of Jet as well.
I am having a lot of issues when running Jet Reports - I am writing the report and everything looks okay but once run they look like this:

But the rows are running - when i drilldown the values appear

I am running the latest version of Jet as well.
This is more than likely a time-out issue. You can increase the timeout in your data source settings but that may also require the change within your SQL database, too.
Not an ideal solution, but you can try turning off Enable batch function execution in App Settings->Performance. This isn't ideal for two reasons. First, it could make the report slower to run. Second, if all the other reports you have work and this fixes this one, you will want to turn this on and off depending on the report you are running. It is always best to have this on.
Ultimately, this could also be a design issue. If it isn't designed using best practices, there may be an error occurring causing the timeout that then cascades to the other functions.