An undefined technical issue on Pleo's side.
Please try disconnecting and reconnecting e-conomic:
Go the "Accounting" page in the Pleo web app.
Take screenshots of the bank accounts and journals that you have already entered on that page, so that you know which numbers to input after you reconnect.
Click on the "Connected" button underneath the logo of e-conomic.
Follow this guide to reconnect to e-conomic.
If disconnecting and reconnecting doesn’t work, please contact Pleo's support team.