Jungles do not work as expected on real devices

I have no problems using jungles inside my test environment - all sim test devices do work.

Setup

My setup looks like following:

project.manifest = manifest.xml

srcBase=source
resBase=resources

# Standard - für auto build
base.sourcePath=$(srcBase);source-fenix6x;source-280x280
base.resourcePath=$(resBase)

# --------------------
# GROUP 280 - Fenix 6X 
# --------------------

fenix6xpro.sourcePath = $(srcBase);source-fenix6x;source-280x280

# -------------------
# GROUP 260 - Fenix 6
# -------------------

# Fenix6
fenix6.sourcePath = $(srcBase);source-fenix6;source-260x260
fenix6pro.sourcePath = $(srcBase);source-fenix6;source-260x260

# -----------------
# GROUP 240.A - MARQ
# -----------------

# Info:
# seem to be different than other 240 devices - do support smaller fonts by default already
marqadventurer.sourcePath = $(srcBase);source-marq;source-240x240-marq
marqathlete.sourcePath = $(srcBase);source-marq;source-240x240-marq
marqaviator.sourcePath = $(srcBase);source-marq;source-240x240-marq
marqcaptain.sourcePath = $(srcBase);source-marq;source-240x240-marq
marqcommander.sourcePath = $(srcBase);source-marq;source-240x240-marq
marqdriver.sourcePath = $(srcBase);source-marq;source-240x240-marq
marqexpedition.sourcePath = $(srcBase);source-marq;source-240x240-marq

# ---------------------
# GROUP 240.B - Fenix 6S
# ---------------------

fenix6s.sourcePath = $(srcBase);source-fenix6s;source-240x240
fenix6spro.sourcePath = $(srcBase);source-fenix6s;source-240x240

# ---------------------------------
# GROUP 240.C - Fenix 5 (without 5S)
# ---------------------------------

# Info:
# needs small custom font!

fenix5.sourcePath = $(srcBase);source-fenix5;source-240x240-f5
fenix5plus.sourcePath = $(srcBase);source-fenix5;source-240x240-f5
fenix5x.sourcePath = $(srcBase);source-fenix5x;source-240x240-f5
fenix5xplus.sourcePath = $(srcBase);source-fenix5x;source-240x240-f5
fenix5splus.sourcePath = $(srcBase);source-fenix5s;source-240x240-f5
fenix5.resourcePath = $(resBase);resources-small
fenix5plus.resourcePath = $(resBase);resources-small
fenix5x.resourcePath = $(resBase);resources-small
fenix5xplus.resourcePath = $(resBase);resources-small
fenix5splus.resourcePath = $(resBase);resources-small

# ---------------------------------
# GROUP 240.D - Forerunners
# ---------------------------------

# Info:
# nur 645, 935 braucht kleine custom font

fr245.sourcePath = $(srcBase);source-fr245;source-240x240-fr245
fr245m.sourcePath = $(srcBase);source-fr245;source-240x240-fr245
fr645.sourcePath = $(srcBase);source-fr645;source-240x240-fr645
fr645m.sourcePath = $(srcBase);source-fr645;source-240x240-fr645
fr935.sourcePath = $(srcBase);source-fr935;source-240x240-fr935
fr945.sourcePath = $(srcBase);source-fr945;source-240x240-fr945

fr645.resourcePath = $(resBase);resources-small
fr645m.resourcePath = $(resBase);resources-small
fr935.resourcePath = $(resBase);resources-small

# --------------------
# GROUP 218 - Fenix 5S
# --------------------

# Info:
# needs small custom font!

fenix5s.sourcePath = $(srcBase);source-fenix5s;source-218x218
fenix5s.resourcePath = $(resBase);resources-small

The relevant line for the Fenix 5X is following:

fenix5x.sourcePath = $(srcBase);source-fenix5x;source-240x240-f5

I have a file called DeviceInfo.cs inside each source-<MODEL> folder that looks like following for the garmin Fenix 5X (the file inside source-fenix5x):

class DeviceInfo {
	static const DEVICE_NAME = "Fenix 5X";
}

Problem

The Fenix 5X sim shows the correct text in my watchface, namely "Fenix 5X" - this is the text coming from the DeviceInfo class I posted above. But a user reported me that he sees "Fenix 6X" on his Fenix 5X device. Of course I also checked again that the text inside the source-fenix5x folder is correct and it definitely is.

Are there some problems with the jungle based method I use?