You need to export the certificate from the browser. The reason it doesn't work via IP address is because the hostname won't match the IP and it's a system generated certificate, ie, self signed. Usually once you ignore it in a browser it should remember that choice but the behaviour varies.
That's what I did, exported from Chrome (saved to a file), then imported that to MMC. However, like you say, the hostname won't ever match the IP and therefore even though the cert is now saved, it's still an invalid cert in Chrome's eyes (or at least that's my completely ignorant theory). So I still have the 'Not secure' red warning triangle in the far left of the address bar.
I know the quick and easy answer to this is to continue ignoring it like I have been doing until now, but, like I say, it's just grating on me and I'd like to understand how to fix it, if only for my own sanity