It seems that airfields can be defined and uploaded to Skydemon without any QC, which can inhibits issues with flightplans and ATC.

Fx the minor Polish airfield Borne Sulinowo (nice people BTW ) seems to have declared themself as EPBS which is used when an ICAO flight plan is created within Skydemon. However this is NOT an official ICAO destination and ATC therefore rejects the flightplan.
You have either to manually identify the coordinates and adjust with a ZZZZ or you can 'cheat' by select a random location in the neighborhood which then make Skydemon automatically generates a ZZZZ with almost correct coordinates.

Wish/request: in connection with generating the ICAO flight plan, validate that all ICAO abbreviations comply/are in accordance with 'official' definitions. If locations are not verified, either convert to ZZZZ and/or prompt an error message ... or prevent user-defined ICAO abbreviations for airfields.

Thanks for alerting us to the incorrect ICAO identifier, we will investigate the source material and remove it for next week's chart update.