Just following up… Are you still having this issue or has it been resolved already?
If you are still having this issue, I would suggest the following:
1) Temporarily deactivate your other plugins (all plugins except Sliced Invoices) to see if perhaps it’s a plugin conflict.
2) Check your PHP error logs to see if there are any error messages that would give us something to go on.
3) Check your browser console and see if there are any javascript errors.
If there are any errors let me know and I’ll investigate further…
Regards,
David