I completed a workout in my training plan but the workout was stuck on Sync Pending.
When I came back to it the following day it has gone and the workout appears not done. The next workout I did sync’d ok.
Although its not a showstopper its slightly annoying and it would be nice to get it back if possible. I hate seeing red workouts 
I’ll leave my post here but answer it myself in case it doesn’t occur to someone else.
I did the workout on my tablet. The next day my tablet wouldn’t connect to Wahoo (haven’t figured out why yet), so I used my phone.
I can’t get onto my tablet yet but since the sync was still pending its pretty obvious it hasn’t reached yahoo and therefore is not on my phone 
@EzaBlade I had something similar happen. Contact support to see if they can assist. As long as you have the completed workout and the scheduled workout you can link them by dragging the planned over the competed.