Preview and send email not working

Update

Now preview and send email works only on:

Welcome email: Preview >send to email "Sent when a new WordPress user with the role?Customer?is added to your site."

Email to new users - works

Email to new accounts - works

Not sure is because in case of a new user is accepting to send or?because it only works from woocommerce inputs?

Preview and sen email -?Not working:

Welcome email:?Sent when someone subscribes to the list:?Newsletter mailing list?Not working
Email to the new subscriber -?Not working

Email to notify the admin Working (???)

Previous message cancelled by someone:

Unlike few months ago, mailpoet no longer send emails (or very occasionally):

Welcome emails, Posts notification, newsletter.

I then activated the key (free plan/1000 subsc.) but no changes.

Then I tried to use mailpoet email sender in settings

Then I unsubscribed and binned the users and re-added it

In the mean time I flush the cache switching again sending methods and re-subscribe

Nothing worked so far.

I noted that in > setting in >send with > send test email work 100% of the times

But Welcome emails, Posts notification, newsletter > preview > send to email do not work (not in spam either)

When a new subscriber is added and the email is re-activated, it also doesn't work, or only sporadically 5% of the times, with my server or mailpoet that requires to confirm subscriptions.

This still occur with the last updates including WP and no error log / system requirements.

It doesnt seems to be mentioned by many users so far however clues on what's going on would be really appreciated. I Have no system issues with any plug in.