This is the transcript of what Suunto has said on the matterfrom an online chat. They are suggesting it does not work with Catalina.
Wendell (21/10/2019, 00:03:15): I am Wendell, how can I help you?
David (21/10/2019, 00:04:32): I’m having trouble with dm5 on Mac with latest os Catalina. Dm5 won’t load, tried reinstalling but still no joy.
Wendell (21/10/2019, 00:05:59): Sorry to hear that. Let me help you.
Wendell (21/10/2019, 00:06:24): Regarding the issue you're experiencing, I will need to forward this to our team.
Wendell (21/10/2019, 00:07:32): For now, what we can suggest is to use a different computer that has a different Operating system.
Wendell (21/10/2019, 00:07:52): Windows or Mac, but mac shouldn't have the catalina.
David (21/10/2019, 00:10:40): Not possible, don’t have another computr
David (21/10/2019, 00:11:05): i am very disappointed in the stability of dm5
David (21/10/2019, 00:11:45): also all my notes are logged in dm5. What would happen to them.
Wendell (21/10/2019, 00:12:29): Your files will be kept in DM5, so it will be in our server.
David (21/10/2019, 00:12:46): Are you saying if I back update to Mojave’s it should work. Not easy to do.
Wendell (21/10/2019, 00:13:19): We apologize, what I will do is to forward this to our developers and back-office team to be fixed.
Wendell (21/10/2019, 00:13:29): Yes, it should work.
Wendell (21/10/2019, 00:13:48): If you can do that, then it'll be the best option for now.
David (21/10/2019, 00:15:02): if you could, also of course I have lost the ability to update the cores software and make changes on it. Again I don’t think that this is acceptable. I appreciate your not responsible for os updates but all my other software works. I await your teams response.
Wendell (21/10/2019, 00:16:08): Thank you for your understanding, we will work on the compatibility of DM5 to the new Mac Os update.
David (21/10/2019, 00:17:31): my issue with back installing is I have to totally wipe Mac and reinstall from 3 weeks ago, this will mean any data files I have updated in last 3 weeks I need to identify and pull off before I backdate and then re add them to my system.
David (21/10/2019, 00:18:13): If it does not get sorted then I may have to seek a refund.