Some people do seem to have problems loading photos for the first 5 posts. It's not the same for everyone though which I can't work out
I don't know when a rule for this was implemented (or even if it was added purposefully) but we have always assumed it was to stop porn which we used to have a problem with from some new posters.
Usually the problem is size of the photo. Not just file size, but pixel dimensions (height and width). On the PC the screen where you upload them tells you what the sizes need to be.
Another problem can be if your internet connection is not a strong enough signal, or is 'flakey'. If the connection drops during the upload it could cause it to abort. The slower the connection the longer it takes to upload and the more chance there is for a 'glitch' to happen to the connection during that time.
On your android it may be worth trying with TapaTalk app rather than the browser. Some people who have problems with photos find this works better for them. I have a feeling this may actually be a route around any possible 5 post rule, but not worked out if that accounts for everyone who has been able to post photos earlier than 5 posts or not
You can also put the photos on another website such as Flickr or Photo Bucket or something like that, then link to them from here. See the link in my signature for tips on doing that as well as other tips for posting photos.