GPT-4 conversations converting to 3.5

Noticed today while using my saved prompts that they are now converting to 3.5 due to

‘The previous model used in this conversation is unavailable. We’ve switched you to the latest default model.’

Also, when I select a new chat the GPT-4 is sometime there and sometimes not, but mainly it’s only lets me use 3.5 Plus. Only just renewed my monthly subscription last week. Is GPT-4 down or is something funky going on today with OpenAI? Is anyone else experiencing anything similar?

same problem. Just renewed my plan but no GPT-4 available

Are there any solutions now? My chats are still reverting to 3.5.