I have a 3 day old iPhone XR, running iOS 12.4. The phone's name has an apostrophe in it, and the password is all lower case letters. I connected my Sharp Roku TV (OS 9.1.0) to its hotspot without an issue. I don't know if it's the latest iOS update that resolved things, or a Roku update. But I had no issues connecting.
Nvidia Shield, Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.