I’m still having this issue too…is there any update ?
Just started happening on both my Android phone and Amazon Fire Tab. I saw the library for a second and then it turned to “offline”, never to be seen again.
I guess there is no point in paying for Plex Pass if the devs don’t consider fixing mobile as a priority.
I just started having this issue today on my Pixel 2 and my Android TV. Very annoying. The apps were already terrible, now they’re unusable!
Update: They fixed my issue iOS 12 - Plex + OpenVPN - 'Offline' message in Plex iOS. Not offline hopefully this fixes it for some of you
wow, so surprised the thread is soooooo long with no resolve, crazy!? I’ve turned up because I’ve recently got Plex on my iPhone 7 and guess what… no internet connection, jeez
I am experiencing this regularly now. Was sporadic and not as bothersome but now it is fairly constant. Rather frustrating because all I want to do is listen to synced music at work where I don’t have guaranteed signal/access.
Same issue here. 
@DaveBinM Is anyone from Plex monitoring this issue ?
We are monitoring and continuing to investigate.
My OnePlus 3T is also showing media as offline on home wifi
It’s been happening to me quite a bit these days on my iPhone and iPad.
@DaveBinM Is there any update on this issue?
Same beef here since yesterday. iOS 12.0.01.
Can’t play anything from the thumbnails but it will play the video left in the player from last time and will happily autoplay next one too
I am having the same problem on iOS but my issue is different per category. My TV says offline but movies and other video categories work just fine.
I am having the same problem with my IOS devices and Apple TV. Webpage works fine.
On my Ipad running current IOS the app shows offline but I can see my content. Plex server is stand alone PC with no VPN running. I have 3 Roku sticks and they run plex with no issues.
Yep, this happens to me about every 3rd time I start the app.
I guess this is the price of progress!

I think I found my problem. I recently added a few tv shows to the plex dvr using my hd homerun. After deleting the recording schedule and the files (folders and video) it created everything worked.
It’s affecting me also, in both my iPad and iPhone which have both been updated to the latest iOS version. Unlike other’s it’s affecting only my Shows. When I select Shows, it gives the, “Houston, we have a problem…” error. On the home page, I see my recently recorded shows, and can play them from there, but can’t see them when I go into the Shows option. Also, no using VPN, and can see all shows when using the web page in Safari.
Where you see it only affecting libraries that have DVR recordings that’s a different issue, on the server side, that we’re looking into with the beta of 1.13.9, and not related to the rest of this thread.