HEIC isn't a supported image format in Mendix applications. Only png, jpeg, gif, bmp, and SVG are supported.
https://docs.mendix.com/refguide/images/#2-supported-formats
You may be able to write a Java Action to convert the HEIC image to a supported format, or use a microflow to call an online conversion service via REST such as the ConvertImage API at Cloudmersive.
https://api.cloudmersive.com/swagger/index.html?urls.primaryName=Convert%20API
Good luck!