Memory for ChatGPT-4 is great on my account, however 3.5 does not seem to understand that the memory feature exists. It sometimes claims it can remember things between conversations, but it consistently fails to access the memory.
4 is able to read and write to the memory and discuss it with accuracy, and I was not affected by the 'memory randomly disappearing' bug at any point. It's just that 3.5 seems unable to use or detect the memory feature for my account, though 4 is perfectly able to.
Examples of 3.5 issues:
https://chat.openai.com/share/c9d19e0f-bed0-40ec-9d33-061c7aa66a34
https://chat.openai.com/share/efd84f7e-2035-4856-8dfb-42c01593d736
https://chat.openai.com/share/04d7ce88-3193-4da6-a1f3-45ac2569ebcd
For comparison, here's 4, successfully accessing memory on my account: https://chat.openai.com/share/33d1221e-906a-4f83-a917-38d95783dc98