I had this issue and i figure it out.
The text block on Elementor won’t work for ACF url fields. What you need to do is use a title bock instead. Put the tittle you want and select the custom field for the url on the url field on the title block.
Hope you could sove your problem, the only thing is that it wont show the link, just the title but clickable to the custom url fiel.
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