Hello,
we have same problem. Did you perhaps ugrade the project from 5.1 as we did? This could be one of the cause, because it still works in a completely new project.
Enclosing a piece of log for the standalone game regarding the SunSky actor:
Error: FStructProperty::Serialize Loading: Property 'StructProperty /SunPosition/SunSky.SunSky_C:UpdateSun:CallFunc_GetSunPosition_SunPositionData'. Unknown structure.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin SunPositionData no longer exists on node Break <unknown struct> . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Elevation no longer exists on node Break <unknown struct> . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Corrected Elevation no longer exists on node Break <unknown struct> . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Azimuth no longer exists on node Break <unknown struct> . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] No Struct in Break <unknown struct>
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin <Unnamed> no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin <Unnamed> no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Latitude no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Longitude no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin TimeZone no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin bIsDaylightSavingTime no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Year no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Month no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Day no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Hours no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Minutes no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin Seconds no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] In use pin SunPositionData no longer exists on node GetSunPosition . Please refresh node or break links to remove pin.
Error: [AssetLog] C:\Program Files\Epic Games\UE_5.2\Engine\Plugins\Runtime\SunPosition\Content\SunSky.uasset: [Compiler] Could not find a function named "GetSunPosition" in 'SunSky'.