If a profile looks blank, it may not actually be blank!
Fediverse servers work like this: servers only notice accounts from other servers if someone follows or interacts with them. If no one on your server follows a particular account, and that account is on another server, then that account may appear blank to you.
The reason servers work like this because of resources. If servers had to keep a copy of every post from every user on all the thousands of Fediverse servers in the world, their running costs would become prohibitively expensive (and most of those posts would probably never be read anyway).
The idea of the Fediverse is to let anyone start their own server if they want to, and this process of servers “noticing” accounts helps make that possible.
Viewing the latest and most complete version of an account
To check what the profile really looks like, log in to your account through the website, go to the profile, click on ︙ and then “Open original page”. This should open the profile in a new tab on its home server, which will show all the public posts the account has ever made.
Unfortunately, original pages on other servers are more difficult to interact with. By default your have to enter your username and password each time, though there are ways to make it much easier.
How to prevent your own profile from ever looking blank
If you pin some of your posts to your profile, for various technical reasons your profile will never appear blank to anyone as these posts will always be visible. You can pin up to five posts on a profile, and these can include attached photos, video and audio, so they’re a great way of introducing your account to potential followers from any server. Click here to find out how to pin posts.
Backfilling to the rescue?
There’s there may be a possible solution to blank profiles on the way called “backfilling”. This would mean as soon as you follow someone your server would automatically check the account for past posts and display some or all of them on your server. With backfilling there would be much less need to fiddle around with original pages etc. At time of writing backfilling is the most popular suggestion on the Mastodon github site, and if you’re comfortable using github you can go and give it a thumbs up ⧉.
Update buttons to the rescue?
The official Mastodon roadmap ⧉ has an item labelled “Explicit controls to fetch more data from origin server”, which seems to mean they would introduce some kind of update button to fetch the latest version of a profile on demand. It’s in the “Planned” section of the roadmap which means they’re working on it. These would be practically very similar to the backfilling mentioned above.
Accounts with restricted post visibility
An alternative reason why an active account might look blank is this: if the account has follower requests on (indicated by a padlock 🔒 next to their name), and all its posts are followers-only, then you will not see any posts on their profile until you follow them and your follow request is accepted.