Sum in tree view doesn't displayed until the last was activate
The sum of numeric fields in tree view are only displayed when the last record is selected or displayed.
To reproduce it I used the timesheet module:
1. Open Timesheet > Timesheet lines. The Duration Sum are displayed only with "-".
2. Add a filter, in my case, date. I tried with 04/26/2019, 5 records are displayed and the sum is correctly displayed.
3. Add another filter, Employee: Beesly, 105 records are displayed, but the sum display "-".
4. Select the last record and the Sum suddenly is activated.
Also I recorded a sort video of that, maybe is the desired behavior.
https://www.dropbox.com/s/miypwva3i0xoy8r/sum%20on%20tree%20view.webm?dl=0