This floated past on twitter - not seen this elsewhere but have no idea if it is correct or otherwise.
"Boeing 737 Max 8 test flight of #SunExpress TC-SOI (Boeing test reg N1779B). BFI PAE BFI as flight BOE301. Pics from 15 May 2020 at PAE. #Boeing#737Max#BoeingMax#737Max8#B737#SunExpress#PAE"
Sun Express are Turkish and operate in Turkey and to the EU.