Which version are you using ?
(try and install latest, V4.1)

I use the Version 4.1

First, please check for errors in browser console.
If any, please post it here.

Also check that ticket wokflow allows to change status for current user (can you change status in ticket interface ?)

If all is correct, I think there is and issue with some content.
In that case, if you display only few tickets, move is possible.
Could you please try and apply filter (for instance on status, or filtering on name) to find the ticket(s)
NB : you must use filter feature that will refresh items from server, not direct filter fileds that just "hides" items on the page
When you have ideitified tickets that leads to issue please post here its content.

I have no errors in the browser console.
When I have unchecked 'show large elements' then I can move the tickets.
When I have checked 'show large elements' then I cannot move the tickets.

I can change the status in the ticket interface.

I think there is and issue with some content.
In that case, if you display only few tickets, move is possible.
Could you please try and apply filter (for instance on status, or filtering on name) to find the ticket(s)
NB : you must use filter feature that will refresh items from server, not direct filter fileds that just "hides" items on the page
When you have ideitified tickets that leads to issue please post here its content.

I have identified the faulty ticket.
The issue was caused by the text in the description.
See the enclosed picture.

Can you please share content of descrition field ?
(you can use Private Message for confidentiality)

Attached is the content of descrition field.

New version of Kanban plugin (V4.2) has been deployed to fix this issue