iPhone All Mail button not working

Apologies. I don't have that view in my mailbox because I'm not using Categories. I use list view as I don't like the categories view. If you want to go back to list view, tap the circle at the top with the three dots in it and choose List view.

I am not clear why did you crop the image.

To improve my understanding of the phenomenon, it would be highly beneficial if you could share a full screenshot (Do not crop it). Visual representations carry a greater impact than written descriptions.

Please remember that this is a public forum, so when attaching a screenshot, please avoid including any personal credentials such as IP addresses, card details, email IDs, Apple IDs, IMEI numbers, serial numbers, phone numbers, order IDs, or any identifiable location information if you are sharing a map.

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...

Please re-post with detail so that someone else can help.

See this Pic below that may help you. Why I asked you for a Full Screenshot is to see if the Filter icon is full blue which will indicate a filter is applied. The pic below shows the icon only with blue outlines indicating No filters.

JonasGrumby wrote:

Thanks. I think that will solve the issue. I need to see all of my messages.

You're welcome. I don't quite get the category view as like you, I want to see all my messages in the order they were received.

Sounds like something you need to address with Google as they own Gmail, not Apple.