I have an asset (value 0, error by me), 2 depreciation entries.
I then edit the asset. Change the value in 500.
I then get an error about the lockdate when saving the value

I have an asset (value 0, error by me), 2 depreciation entries.
I then edit the asset. Change the value in 500.
I then get an error about the lockdate when saving the value

Same happens when I try to create a new asset with a value other than 0
This isn’t a bug.
The value that appears in the setup of a Fixed Asset is its Starting balance which by definition predates any lock dates the user has set.
In order to edit any Starting balance, you need to remove the Lock Date.
You are right… not sure how this can be more explicit.
I made a mistake by setting the book value, as that will be added by a different transaction (purchase invoice)
But according to your OP, the asset has 0 starting book value and 2 depreciation entries. That’s a bit confusing.
Could you please demonstrate with screenshots the following:
Also, you should provide a description of what is your desired outcomes from all of this as well–spare no detail.