Race predicted time increased but vo2max increased too

What was Training Status after the long run? I could see this happening if you had moved into Overreaching  or even still Productive but very close to Overreaching.

I had to take a few days off recently due to weather and my race predictions went down each day as my Training Status switched from Productive to Peaking, so the opposite could definitely happen as you’re ramping up mileage during marathon training. 

The VO2 Max is one key component of your race predictions. To reach a certain time in a certain distrance you need a certain aerobic capacity.

But it is only one component, the other is how good you are at using this capacity. This is the training history that the watch is taking into account. In the real world, this corresponds to your capacity to manage lactate. For the same VO2 max, the athlete with the higher threshold will win all endurance races.

The best way I found to feed the watch the right info is to run maximal efforts across typical time intervals (let's say 1mn, 4mn, 10mn, 30mn, 1h). If you have Stryd, do the testing plan for example.

The second best option is to keep the training focus balanced as too much bias one way or the other creates a bias in the Ventilation/Pace/Duration relationship the watch is modeling.