I'm using several extended fields with UpdateProfile,
I also ran Extend modUser so all the extended fields are represented in the Manager User Profile page. So far so good.
Updating the profile from the front-end seems to be working fine (so far) with all the extended fields. Everything gets written/updated to the db and Manager page. The two exceptions are the default "website" and "username" fields.
I added the "website" and "username" fields to the profile form,
<label for="username">Username [[+error.username]]</label>
<input type="text" name="username" id="username" value="[[+username]]">
<label for="website">Website [[+error.website]]</label>
<input type="text" name="website" id="website" value="[[+website]]">
with the placeholders:
The problem is both fields revert back to their previous value on save.
Because these are default user fields (i.e. not extended) I assumed it didn't need to be included in Extend modUser.