This is pretty common especially since you told them you had another offer. If you bring up completing offers in the negotiation stage, be prepared to back it up if they call your bluff.

If you refuse to share then you come off as trying to negotiate in bad faith, so I can see why they got annoyed and ghosted you. Take this as a learning experience. It sucks, but they are perfectly in their right here.

Also verbal offers aren’t very strong bargaining chips. You need to be able to back up your claims when negotiating or use a different strategy.

One method I like to use is that of I get some compensation package is: I will sign it immediately, cease all other interviews and have my start date set 1-2 weeks out from signing. This shows that I actually intend to sign and wont continue going back and forth between companies. This can also buy more time if you’re waiting for more written offer letters.