Our puppy seems to be regressing with house training. She's 15 weeks old today and has got in the habit of waiting until she's back inside to go. We're taking her out every hour plus after waking, eating/drinking etc and our timing is right because she'll go as soon as she's back inside. It doesn't matter if she's out there for 5 minutes or 30 minutes, if we put the lead on and stand still ignoring her or if she's off lead and has fun. She used to go outside straight away and I can't think what's causing it. She's also started to eat her own poo
You need to wait with her on the lead until she goes, let her sniff about but no playing. Reward with high value treat. Be prepared to wait for a long time at first, she'll get quicker once she realises she gets a treat for going. Be ready with a bag to grab the poo immediately so she won't get a chance to eat it.