Can you post the crash log that happens when you are trying to load the scene? It can be found inside the "C:\ProgramData\Mount and Blade II Bannerlord\logs" folder.
Also, this map is in your module right? You should not be saving your scene into the SandBox module.
UPDATE
I can load the Main_map into the editor, and save it, but it crashes on campaign start. Ive tried loading the module both before and after Native and it still happens.
The other log is far to long and wont fit here though, is this the one you want?:
Log:
Starting new log file...
[12:53:09.967] 19 Oct 2020 Monday 12:53 GMT Summer Time
[12:53:09.967] Computer: DESKTOP-HB0N7TQ User: lost_
[12:53:09.967] Build Version: 243624
[12:53:43.028]
<##########################################################################################>
[12:53:43.028] #kernelbase.pdb@{C1F1DEA06E0602EBC5B848F55576F84A} (1): 0:147017
#clr.pdb@{FC3F6A2A5E7D437D9AD70E4F2D82B4AD} (2): 0:4585
#clr.pdb@{FC3F6A2A5E7D437D9AD70E4F2D82B4AD} (2): 0:4635
#clr.pdb@{FC3F6A2A5E7D437D9AD70E4F2D82B4AD} (2): 0:4645
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
@unknown_module@unknown_source (unknown_line): unknown_function
#clr.pdb@{FC3F6A2A5E7D437D9AD70E4F2D82B4AD} (2): 0:8750
#Rgl.pdb@{02D48C0BC9BD42A48955A7C72402B8F4} (1): 0:4497208
#Rgl.pdb@{02D48C0BC9BD42A48955A7C72402B8F4} (1): 0:4495604
#Rgl.pdb@{02D48C0BC9BD42A48955A7C72402B8F4} (1): 0:4434565
#Rgl.pdb@{02D48C0BC9BD42A48955A7C72402B8F4} (1): 0:4288694
#Rgl.pdb@{02D48C0BC9BD42A48955A7C72402B8F4} (1): 0:4287931
#Rgl.pdb@{02D48C0BC9BD42A48955A7C72402B8F4} (1): 0:4291255
#ucrtbase.pdb@{EE98F0843F40858DC51E8E564ADED5DF} (1): 0:136386
#kernel32.pdb@{89C3B9FD1C796A0F430E0CEF0646F003} (1): 0:94164
#ntdll.pdb@{01DEFFF845AAA742EA34488610D487CB} (1): 0:315073
-----------------------------------------------
#TaleWorlds.DotNet.AutoGenerated.pdb@{735ED0F010074BBB935433A710D339E4} (1): 100663315:0
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100667558:0
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100667600:449
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100667582:32
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100672312:52
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100664178:13
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100664780:15
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100664315:19
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100663909:0
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100664019:49
#TaleWorlds.CampaignSystem.pdb@{DF5DF0D0ADD74555B9E257C63A06350F} (1): 100664020:413
#StoryMode.pdb@{B881AC85F4ED4CBC947C46EC9E98825F} (1): 100663306:8
#TaleWorlds.Core.pdb@{B1603E0192CF4C9DA5F7080876E9085C} (1): 100664639:131
#StoryMode.pdb@{B881AC85F4ED4CBC947C46EC9E98825F} (1): 100663389:313
#TaleWorlds.Core.pdb@{B1603E0192CF4C9DA5F7080876E9085C} (1): 100664486:220
#TaleWorlds.MountAndBlade.pdb@{72279C1EF9E54C248DECD70F12CAF4D0} (1): 100668564:15
#TaleWorlds.Core.pdb@{B1603E0192CF4C9DA5F7080876E9085C} (1): 100664579:41
#TaleWorlds.MountAndBlade.pdb@{72279C1EF9E54C248DECD70F12CAF4D0} (1): 100671016:149
#TaleWorlds.DotNet.pdb@{DB6DAA5A32784BA197EC148F296AA91A} (1): 100663416:56
[12:53:49.102] Dump generation canceled by the user.