In case anyone else is having this problem despite following DGUIs patching instructions, I just found the cause and solution:
The reason why this happens is that there are mods on top of DGUI in JGSME's loading order that also have their own sh3.exe, in this case here it's EnvSimAct_10 if you used the EnvSimAct_10 folder from the NYGM package . So you might have applied the tychopatch to the sh3.exe in DGUI, but if the sh3.exe in EnvSimAct_10 is unpatched, the problem with the split map occurs because JSGME replaces DGUIs sh3.exe with EnvSimAct_10s sh3.exe
I have another problem, though. The commands for crew on deck, pennants etc don't work
Any ideas why? Here's my mod list:
NYGM Tonnage War V2.5 – Stand Alone Version
NYGM3_New
NYGM3_6F
NYGM_2017A
IABLShipsforNYGM_New_Thomsen
Restore Gods Eye View
NYGM_HiRes_Submarines_3_6F
DGUI_v1.4
Supplement to V16B1 (JSGME)
EnvSimAct_10
Fifi_Enhancement_NYGM
U-Tankers & Harbor_Traffic
Dark_Night_Fix_NYGM