Default text in first page style

Hello everyone,
I saved the following first page in my template (I drew red shapes to hide personal info), but it doesn’t work when applied to a document : the page becomes blank, as if I didn’t change anything to it.
Is there a way to replicate the text I wrote on the first page of my template to any ODT please ?
Thanks in advance for your replies.

OS : Linux Mint 22.1 (Cinnamon)
LO 25.2.1.2
Using ODT and OTT files

Initial contents is automatically inserted in the document when you instantiate the template. If this “initial contents” is created after your document was created, “initial contents” is not transferred into the document because it could cause data loss. Only style modifications are synchronised with the document.

If you can’t figure out what went wrong by yourself, send me your template through private mail for analysis. Click on the icon left of my name. A dialog pops up with a Message button.

Good explanation, I indeed tried to apply the template to an existing file ; thanks