Further Update added Thursday Morning at 08.27(UK time)
Hi Guy,
Reflecting on this again in the morning, when I've had a cup of tea and my brain has woken up a bit, the sudden drops in altitude on the track profiles almost certainly reflect drops in connectivity - either between your phone and available cell towers on your mobile network or between your PilotAware and local ATOM, OGN or other sites, though the reasons for these drops can be complex and warrant further investigation.
I will send you a PM.
Regards
Peter
