Bear in mind the OP told her DH to email her if there was anything, and he did, several times according to the OP but because she didn’t see them she ignored them, the very way her DH tried to speak to her which she told him she would respond to.
A lack of response generally suggests that someone is busy, particularly when you've already been forewarned that they're going to be working, not that you should interrupt them to make an unimportant announcement while they're on a call.
Fact is, if you’re working from home it takes adjusting on both sides. It’s unreasonable to expect that your home working environment is going to be exactly the same as your work environment when it has never been like that before. It isn’t.
If you respect each other's space, you can get pretty damn close though.
DP and I both WFH right now. I've successfully managed to not walk into the (normally shared) office uninvited during his work day. If I'm making a drink I'll text him and offer but if he doesn't respond he just has to make his own. Likewise, he doesn't come downstairs and disturb me in my workspace, and will either pop his head around the door very slightly to see whether I invite him in or will send me a message to ask first unless I've expressly said I'm not that busy and I keep the door physically open.
No drama at all. It's really not unreasonable to expect to be undisturbed when you don't have young children in the house. If I'm at work and I don't respond to DP he doesn't start calling me, he assumes I'm busy/in a meeting and am therefore not available. The same should apply at home.
When he walked in and she said she was busy he should have perhaps left then but there has to be middle ground because like it or not the bedroom cannot be commandeered as an office indefinitely.
There really isn't any 'perhaps' about it in my mind. He wasn't coming in because it was very late and he wanted to go to sleep, or quietly collect something he desperately needed which would have been annoying but much more forgivable. It makes no difference that it was the bedroom at all. He was interrupting so he could have Op's attention, and would have done the same anywhere.
His bike ride could have waited if it was absolutely essential to tell Op. At the moment people are very forgiving about interruptions from pets and children (which is definitely a positive). An adult is capable of waiting. I'd be mortified if DP barged in and interrupted a meeting and ignored my protestations because he had to tell me something non-urgent, especially if I had made it clear I wasn't free to talk.
hey, I just wanted you to know that I'm popping out on my bike for a bit, we can eat when I get back". Fine, surely?
I'm not sure it is fine though. I find it really strange that anyone thinks it's acceptable to come in and talk to someone who is in a meeting/on a call, regardless of how nicely they speak. It's still a clear indication that they consider what they have to say to be more important than your work. What if Op missed something important? Unless what you have to say is incredibly urgent ('darling there's a fire in the kitchen, we need to evacuate' springs to mind) I don't understand why it can't just wait until the call ends. I could maybe see it if he opened the door a crack and indicated 'I'm going out' or dropped a note next to her (off camera) so she could read it when she had a second, but even still it would be rude.
If Op hadn't already told him she was busy on a call until 7 I'd have had more sympathy.