If I enter an encoded URL in a text field, the encodings are removed.
For example, if I enter this: https%3A%2F%2Fwww.example.com
it saves this: httpswww.example.com
I need it to save what I entered, without changes.
I found a workaround: the value is correctly saved if I use the inline edit on that field in the post listing (via the Admin Columns plugin). That seems proof that MetaBox is changing the value if I edit the field when the post is in edit mode.