UPDATE: Facebook states that, “Sometimes when we do maintenance on the site, certain photos or albums temporarily disappear. If you’re missing photos, please wait for a few hours to see if they reappear.” However, if you continue to see the blank boxes, you can report it to Facebook using this link.
There seems to be some sort of bug on Facebook where users are complaining that some of their photos in their albums have gone missing. Users are stating that the photos are replaced with blank boxes, although there is no error displayed.
The exact cause of this issue is not known, but we think that it is a bug, or there could be some technical problems with Facebook servers. However, if you’re one among many who are facing this issue, there’s a temporary solution for this. You simply need to turn off the “Secure Browsing” feature, and your photos should be back again. This is a temporary solution, and many users have confirmed that it is working and their photos are visible now.
To disable Secure Browsing, navigate to your Account Settings and select the Security Tab on the left sidebar. From the first option, disable Secure Browsing. Try reloading your album page and see if the solution is working or not.
If the above solution isn’t working, then you will have to wait until the issue is fixed. Facebook is aware of this issue and is probably looking into it.