My second thought is that that: uh-oh, you've got a culture problem, not a remote work problem.
Remote work changes certain work patterns. Innovation bull sessions often emerge from a pressing need, and you want to grab someone right awat]y. In an in-office environment, there are norms built up around use of IM, e-mail, invites, and dropping by someone's workspace. If you have a burning problem and knock on someone's door, it's hard to turn them away and focus on your own problem instead. With an IM, it's much easier to schedule them for later.
One of the more unnatural things in a remote environment is to have to actively accept getting randomized- if some IMs you, check it immediately. Or, god forbid, if someone calls you without IM'ing first (this is functionally equivalent to knocking on door, BTW). I've found once new to remote workers on my team accept that it's the team norm to get a little randomized by others then we get past some collaboration humps.
Since you didn't provide a lot of details, let's assume that I'm wrong and you can easily get your colleagues to spontaneously meet with you. It might be a tooling issue. I've gotten huge mileage out of just screensharing, but there are better ways to collaborate. If you are talking about code, then simultaneous edit tools like VS Live Share can really help. If you are diagraming, there are number of whiteboard like environments available for tablets (or you can get something like an MS Surface Hub for each employee, which is a bit expensive.) I've also had success with just throwing Visio on the screenshare.
Finally, some aspects of remote work are just changing perception of success. Remote bull sessions aren't as FUN as in person bull sessions, just as simulcasting a movie at home with friends or family just isn't the same as watching it in person. That doesn't change anything about the movie. Are you having problems with the solutions you are producing, or do they just FEEL less exciting?
Successfully managing work remotely often means being more formal about measurements or processes than we are in person- do you have evidence that you are solving problems at slower pace, or less effectively? If not, why do you feel innovation has decreased?