Can't find activity in app

Hi

I have set up an activity for my volunteers to join. However it cannot be found in the app. 

When I am in my app it confirms I haven't joined any activities, I search for activities to join and my activity doesn't appear in the search results. 

However I know I have joined the activity with my personal account.

I've logged out and back in again. 

I've sent myself an invite to the activity but this sends me to the webpage version and then tells me 'there is no need to join this activity as I am already a member'

I've checked the settings of the activity and all seem correct to me. 

How do I make the activity searchable and joinable in the app?

Many thanks

Cat