I have just had this issue, having deleted some images from the upload folder a couple of image boxes simply didn’t have the upload option. On Chrome I went in to the inspector and found the div/css for ‘.acf-image-uploader .no-image’ – this was set to display:none; – I just unticked the property and the option to upload an image came back, uploaded the image and happy days, everything was back up and running as normal. Worked for me, Hope this helps in some way…
