I’ve seen there are a few other issues related to this and sent support a message a few days ago but haven’t heard anything back yet, so trying my luck here:
SSL works well with render URL:
https://wtw-frontend.onrender.com/
But it doesn’t work (not secure) with my custom domain.
Already tried to delete and re-add, no luck.
Domain is registered with Google Domains, there is no ALIAS so I set an A record pointing to the given IP
Any help? 
Hi @chrisid, I’ll be happy to help with this. Sorry we missed your earlier support message. Where did you submit it?
It should be working now! Let me know if you continue to see any issues. We had to update a DNS record so the fix may take a short amount of time to propagate.
I’ll investigate why we didn’t respond to your initial email. We normally reply within 1 business day.
It’s my pleasure @chrisid.
I found your original email in the spam folder. Sorry about that. I created a filter to prevent this from happening again if you email us in the future.