Export feature yields corrupted PDF when chart is scrolled down

[matsbryntse]

Forum post

Hi!

This is quite simple to replicate:

Open the Export demo
add the row number column for quick visual result:

        { type: 'rownumber' },

Now the important step: scroll down the Gantt. Make it all the way down just to be sure.
Hit the export button, and validate

Results:
The exported PDF shows rows starting at 21, goes to 41 then starts again at 21 and stops at 40
So rows from 1 to 20 are missing
Most Gantt elements are missing from the first group of rows.

Expected:
Starting row is 1
all rows and their Gantt elements are visible.

Additional info:
RootCause link: https://app.therootcause.io/5fe1fa3cc89e45115095fdf27fb3f0dd68eea198
This is similar to viewtopic.php?f=52&t=14330

[bmblb]

This is essentially duplicate of #933