This will be a function of the end-point of the VPN.
You have two normally isolated networks. You are using one of them, but want to use the other. A VPN allows you to "tunnel" into the other one.
Once you are in the second network, your routes to other places are determined by that network. So my guess is that the network your OpenVPN lands is not set up to allow access to Atlassian.com
This is not unusual - some of the VPNs I've got will do odd things to my networking. One of them is a secured site which basically has no outgoing internet access. Fire up the default VPN into that and all my internet access stops. Another one makes it impossible to use MS-Teams or Skype, but works fine with most other video chat systems. Another one stops all my personal email except gmail. The best one blocks all the outgoing internet connections from the endpoint because I have arrived from the VPN and they don't want me using them to mask my location (when I'm actually inside that network, it's fine, and you can tell this one what you want to VPN, so everything else carries on working from home)
You'll need to look at the networking on the end of the VPN that you are tunnelling into.
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