Scroller stops loading when scrolling up a bit on serverside

Aroc

Link to test case: https://jsfiddle.net/kcp0fyja/
Debugger code (debug.datatables.net):
Error messages shown:
Description of problem:

Hello.

My table has serverside processing, and has around 50k rows.
i set displayBuffer to 20 (i dont understand how/why it loads like 380 rows when the value is 20, but its fine by me). Also boundaryScale is on 0.5, so it should load the next rows as soon i get over half of the current ones.

When i open the Table, it sends 2 ajax request:
1: start 0, length: 20
2: start 0, length: 380

This means, it should load the next rows as soon i go over 190

As soon i scroll a bit, it loads the next rows.

The problem now is, when i scroll until i trigger the new rows, and then scroll back up, and even scroll down further before the ajax request is over, its kinda "bugs out".

like those are then next requets it made:
3: start 2, length 380
4: start 94, length 380
5: start 202, length 380
6: start 214, length 380
7: start 322, length 380
8: start 356, length 380

As you can see, its loaded until row 736.

But in the attached screenshot, you can see that i already scrolled until rows 725-743. Those where never loaded, and will never be loaded until i scroll them complete out of scope and back in.

The JSFiddle example is the exact code from https://datatables.net/extensions/scroller/examples/initialisation/server-side_processing.html, with the exception that the callback only fires after 500ms (so you have time to reproduce the bug)

https://i.imgur.com/r6fUgiW.png
https://i.imgur.com/Q4N15Cn.png

Anyone got an idea what i could do to fix this bug?