"Fatal Error" when executing timeline in build

I have a bit of a large level on a networked game where I use a lot of timeline nodes in BP. Every now and again when a timeline executes on a build I get “Fatal Error” and the game crashes. In the PIE there is rarely a problem.

Sequences or bone animations really don’t make a lot of sense for what I need to do and they seem like overkill. Sometimes it’s just lifting a gate up and down or animating a collectible out from a hole along a spline.

Are timelines in blueprints notoriously buggy or very expensive? Any idea what I could use instead? Or any idea what could be causing these crashes? I’m on 4.20 at the moment but have been experiencing these crashes for a couple versions now…

Thanks for any info!

This is in the .log:
[2019.01.15-21.49.34:651][530]LogWindows: Error: [Callstack] 0x00007ff7869197a2 ScrumProject.exe!UnknownFunction []
[2019.01.15-21.49.34:651][530]LogWindows: Error: [Callstack] 0x00007ff78677cee9 ScrumProject.exe!UnknownFunction []
[2019.01.15-21.49.34:651][530]LogWindows: Error: [Callstack] 0x00007ff783d077f8 ScrumProject.exe!UnknownFunction []
[2019.01.15-21.49.34:651][530]LogWindows: Error: [Callstack] 0x00007ff783d173ec ScrumProject.exe!UnknownFunction []
[2019.01.15-21.49.34:651][530]LogWindows: Error: [Callstack] 0x00007ff783d1744a ScrumProject.exe!UnknownFunction []
[2019.01.15-21.49.34:651][530]LogWindows: Error: [Callstack] 0x00007ff783d24f86 ScrumProject.exe!UnknownFunction []
[2019.01.15-21.49.34:651][530]LogWindows: Error: [Callstack] 0x00007ff787f47286 ScrumProject.exe!UnknownFunction []
[2019.01.15-21.49.34:651][530]LogWindows: Error: [Callstack] 0x00007ff957273034 KERNEL32.DLL!UnknownFunction []
[2019.01.15-21.49.34:651][530]LogWindows: Error: [Callstack] 0x00007ff957ca3691 ntdll.dll!UnknownFunction []
[2019.01.15-21.49.34:651][530]LogWindows: Error:
[2019.01.15-21.49.34:664][530]LogExit: Executing StaticShutdownAfterError