@Slaminger if you have downloaded the vim4 code,please edit the mk file to add file manager.The mk file path is codePath/device/khadas/kvim4/kvim4.mk.
device/khadas$ git diff
diff --git a/kvim4/kvim4.mk b/kvim4/kvim4.mk
index febeee7..9128e5f 100644
--- a/kvim4/kvim4.mk
+++ b/kvim4/kvim4.mk
@@ -49,7 +49,7 @@ PRODUCT_COPY_FILES += \
PRODUCT_COPY_FILES += \
device/khadas/$(PRODUCT_DIR)/permissions/tv_core_hardware.xml:system/etc/permissions/tv_core_hardware.xml
$(call inherit-product, device/google/atv/products/atv_mainline_system.mk)
@@ -236,6 +236,7 @@ PRODUCT_PACKAGES += \
KSettings \
KTools \
SchPwrOnOff \
+ DocumentsUI \
LatinIME
Or you can download the old firmware that contain file manager.And we will fix this bug as soon as possible.Thanks for your feedback.