I have the same problem; I also get multiple arenas, which I thought was the root of the problem, but maybe not. I've also gotten CTD errors on a generic cave quest marker. I enter, fight some wolves, then bam!, flushed to the desktop with no record in the error log. The only trace I'm finding is in the Application event log:
Faulting application name: LegendaryHeroes.exe, version: 2.0.0.0, time stamp: 0x5a4d31df
Faulting module name: MSVCR80.dll, version: 8.0.50727.6195, time stamp: 0x4dcddbf3
Exception code: 0xc000000d
Fault offset: 0x00008aa0
Faulting process id: 0x257c
Faulting application start time: 0x01d3c0a616f08d02
Faulting application path: D:\SteamLibrary\steamapps\common\FE Legendary Heroes\LegendaryHeroes.exe
Faulting module path: C:\Windows\WinSxS\x86_microsoft.vc80.crt_1fc8b3b9a1e18e3b_8.0.50727.6195_none_d09154e044272b9a\MSVCR80.dll
Report Id: afb018e0-2cb1-11e8-83cf-94de80633ebb