Multiple plugin login

My site, https://adsler.co.uk, has four main content catagory areas.

1. Classifieds
2. Dating
3. Jobs
4. Events.

Each area has its own plugin which manages it.

The issue I’m having is that, whilst logging in to admin, and registering and logging in to classifieds both work, logging in to datingand jobs doesn’t.

In dating and jobs, registration and account creation work, but as soon as it comes to logging in with their new credentials, the site just directs the user back to the homepage.

What’s the fix for this please?

Thanks.

The page I need help with: [log in to see the link]