People ask questions in a community when the reward (the answers) exceeds the cost (effort, uncertainty, shame, etc…).
If you want more questions, you need to reduce the perceived effort and increase the perceived reward.
After a decade in community consulting, I’ve almost universally found the most effective approach is to change what it means to ask a question.
Right now, many of your members feel asking questions is an admission of weakness, ignorance, or some sort of failure to not already know the answer.
The big win is persuading members that asking questions is what the smartest people do, it’s the secret sauce that turns amateurs into professionals.
If members feel asking questions is the only way to get access to the knowledge that can’t be taught, a habit of smart people, and the key to rapid improvement, they will ask a lot more of them.
This means you need to rebuild a member’s sense of identity where smart people aren’t the ones who never admit not knowing the answer, but instead, are the ones brave and wise enough to ask questions.