Can't access Tags in landing pages / can't upload templates landing pages

For an unknown reason, I can’t access my Tags in the form of my existing landing pages, it says “no data”
I also can’t upload my templates landing pages in order to create a new landing page. The system is like bloked, it is like uploading forever (I waited 15 minutes without any change).
Could someone help me with these issues ?
Best regards,
Eric Graf