A number of custom link field modules (including Core's 'link' field) provide a token that resolves to the URI but not the URL. If you are attempting to generate a valid 'href=' from such a token, you can't, as the result for an internal link will have an 'entity:' or 'internal:' prefix.
It would be nice to be able to replace the URI from such a token with the actual URL.
See attached PlugIn for this module, which does this.
For an example custom link field 'field_link' with the URI token:
[field_link:uri]
the token modifier that uses this plugin would be:
[token-modifier:uritourl:field_link:uri]
Active
2.0
Code
Thanks for the plugin, @kmv.
I don't think there will be a enough need for this modifier but I will link to this issue from the project page so people can find the code if they need to.