Garmin Coach changing workouts throughout the day

Is your target for the half marathon within reach vs your current fitness level? i.e.not too ambitious. It sounds like the garmin training plan is trying to build your base fitness first before giving you more difficult runs, otherwise the training load will be too much. Have a look at your running load. 

FYI you can select and bring forward any workout you see in your daily suggestions list, like an interval in your case that is scheduled for later in the week and run that today, look at you daily suggestions list and select what you wish to do, then "Do workout" option

Is your target for the half marathon within reach vs your current fitness level? i.e.not too ambitious. It sounds like the garmin training plan is trying to build your base fitness first before giving you more difficult runs, otherwise the training load will be too much. Have a look at your running load. 

FYI you can select and bring forward any workout you see in your daily suggestions list, like an interval in your case that is scheduled for later in the week and run that today, look at your daily suggestions list and select what you wish to do, then "Do workout" option

For me it is the opposite. I have the target in the training plan set on 2:15 but Garmin claims I can do 1:50 and is clearly pacing the base runs for that time.

I would prefer that they advise a faster target based on my results but let me decide if I want that.

Strange its pacing your easy runs faster than the half marathon pace target, they should be slower.

What does it say your training status is? Productive, unproductive, overreaching etc?

Also Acute training load, is its status Optimal?

Force one of the intervals or long runs it has planned later in the week for earlier in the week and see how you get on and how the training plan responds.

Strange its pacing your easy runs faster than the half marathon pace target, they should be slower.

What does it say your training status is? Productive, unproductive, overreaching etc?

Also Acute training load, is it's status Optimal?

Force one of the intervals or long runs it has planned later in the week for earlier in the week and see how you get on and how the training plan responds.

Training status has been maintaining for the past 4 weeks, after a month on productive. Load is between 650 and 1100, with the ratio circling around 1. Load focus is almost exclusively high aerobic (210 an, 2904 high, 324 low).

I did go for a run with some colleagues two days ago, ignoring the training plan, and today it actually scheduled a sprint. Will definitely be doing that.

Load focus targets are different person to person but it appears your High Aerobic is way higher than the Low Aerobic, almost by a factor of 10x. I suspect its telling you High Aerobic overage or something to the effect.

Enjoy your sprint session today, but next time it gives you a base run, just run it slowly, no matter what its telling you the pace is, keep your HR Zone 3 (green one). That'll give you more Low Aerobic which will balance out and free up capacity for the intervals and long runs etc.

This is very helpful because often the tempo or interval suggestion was bumped to the next week. Thanks!

Yep, it's total madness, unusable.

Thought I'd give it a try, been training for years off set plans.

Three weeks in, this isn't workable, changes on the day and the entire week's schedule without any way to select the workout that was planned originally, or rejig if required.

And per the other comments, it's way too quick to jump back to base / recovery sessions.