Why do my employees seem unmotivated to attend team-building activities when they have a flexible work schedule and can choose their own projects?

I totally get why you're concerned about low participation in team-building activities, especially when you've given your team the flexibility to work on their own projects. From my own experience working with remote teams, I've found that it's not uncommon for team members to feel disconnected from their colleagues when they're not in a traditional office setting.

One thing that might be contributing to the low attendance is that your team members might not feel obligated to participate in team-building activities since they're not required to be in the office. But don't worry, there are still ways to encourage team engagement and motivation without relying on traditional team-building activities. For example, you could try hosting virtual happy hours or social events that are optional, so team members can participate at their own pace. Another idea is to create a virtual 'watercooler' space where team members can connect and chat with each other in a more casual setting.

As for adapting team-building activities to a flexible work schedule, I think the key is to make things as low-key and convenient as possible. For instance, you could create a shared online calendar where team members can sign up for activities that interest them, so they can participate at a time that's convenient for them. You could also try hosting online workshops or training sessions that are relevant to your team's work, and that way, everyone can participate at their own pace.

Oh, and one more thing - don't underestimate the power of simply checking in with your team members regularly. As a remote team owner, it's easy to get caught up in managing projects and workflows, but taking the time to connect with your team members on a personal level can go a long way in building morale and motivation. Even just a simple 'hello, how's it going?' email or video call can make a big difference!