I have this datatable:
http://webix.com/snippet/ab5abc63
as you can see, when user change pages there is something wrong with table.
I see there are at least two problems - first due to spans, and second (if you comment spans section) - wrong size when switch to second page.
Probably some adjustment command needed, I tried many different (adjust, resize, refresh, etc) with no luck
I can confirm the issue, thanks for reporting. We will provide the fix in the next version.