It takes time to view the images on thumbnails, and everytime, now and then, it keeps on refreshing the thumbnails pictures of the files and that takes quiet a time to show all the thumbnails of all the stored pdf books in ios(ipad pro 11).
But this doesn’t happen in Android,the thumbnails of the pdf files are stored permanently even when restarting the adobe reader app.
The picture preview, as Thumbnails, of pdf books shows a beautiful cover page image of the file which is aesthetically important and motivating for readers.
Please fix this bug of continuous refresh of thumbnail images of the stored files.