Local vs XAMPP. Image cropping problems on Local

I am testing the Ultimate Member plugin, and what I found is that if I am using Local by Flywheel, I can not test my site properly on my iPhone via the ngrok link since the image cropping function does not work. If, on the other hand, I use XAMPP for testing, all works very well. The settings are equal on both i.e. Apache 2, PHP 7.1.3, MySQL etc.
Any ideas as to why ?
Many thanks!