contact form not working

Hello :)
I am having problems with the contact form on a coming soon page for a new client. A few details of the process are below:

* The clients hosting is on a plesk platform (I am not sure if this matters but all my previous sites were on cPanel.)
* I uploaded WordPress and increased the PHP setting to v7.3.18 in the plesk platform (it was previously v5.3).
* I went into wp-admin uploaded Enfold, put the site in maintenance mode and set up a coming soon page.
* The contact form on the coming soon page isn’t working, we have tested emails from a few different addresses and only 2 went through.

I am trying to get support from the hosting company but to be honest it has been over a week and I am not getting anywhere … really hoping you might have an idea on what might be wrong :)

Happy to provide login credentials to website if you need.

Thank you
Peta