One of the hard things about counting VO2max time in non-structured training (races/group rides) is that the algorithm is counting all the time you spend at VO2max power, but as we all know riding in a group can result in many short duration spikes in power. This won’t elicit the same adaptations since you may not be spending enough time to cause very hard breathing.
As for specifics on how to improve it, this is something I’ve been looking into myself since I also think my FTP has been “capped” by my previous lack of VO2 work. @chad has a post about this concept of doing a focused block on VO2 work to help address it for those of us that need to specifically address it.
In about a month I’m considering doing a 3 week block to get going again for the fall events here in AZ after 1 week vacation and it’ll have 2 dedicated VO2 days and a group ride/race simulation each week, I think Chad’s recommendation in the post is targeted at a shorter block of 1 or 2 weeks with 3 or more VO2 sessions per week. I’ve just started building this out in my Calendar with Tuesday being short anaerobic efforts stacked together and Thursday being 3-5min efforts.