As per log segment below, ATC gave QNH as 1018 and my copilot responded with 1013. Haven't seen this before. 

Program StartedPilot 2 ATC (P2A) - version 2.5.0.5_x64_R3  10/13/2018 13:32:49
Application frmP2AMain starting 10/13/2018 13:33:28
Loading Form
Main form opened: Pilot2ATC 2018 v. 2.5.0.5_x64_R3      Navigraph - AIRAC cycle: 1811

AudioInterrupts: 1 in InterruptAudio 15:46:27
ATC Speak:  SHAMROCK Four Two Two Descend to cross KOKSY at Flight Level One Eight Zero then descend via the KOK Seven Alpha  arrival  with the KOK transition  QNH is One Zero One Eight at BRUSSELS NATIONAL15:46:27
Sug Resp:  ~~Will cross KOKSY at Flight Level One Eight Zero then descend via the KOK Seven Alpha  arrival  with the KOK transition  QNH is One Zero One Three15:46:27
OnTTSWavePlaybackStopped 10/13/2018 15:46:40
UnInterruptAudio in OnTTSWavePlaybackStopped SugRes:~~Will cross KOKSY at Flight Level One Eight Zero then descend via the KOK Seven Alpha  arrival  with the KOK transition  QNH is One Zero One Three SHAMROCK Four Two Two
 10/13/2018 15:46:40
AudioInterrupts: 0 in UnInterruptAudio 15:46:40
InterruptAudio in SayItSpeak- Phrase: Will cross KOKSY at Flight Level One Eight Zero then descend via the KOK Seven Alpha  arrival  with the KOK transition  QNH is One Zero One Three SHAMROCK Four Two Two
 10/13/2018 15:46:40
AudioInterrupts: 1 in InterruptAudio 15:46:40

Thanks for the report.  I believe I found the bug causing this and it will be fixed in update 2506.

Dave