Ref
https://forums.bohemia.net/forums/topic/186322-arma-3-units-feedback-thread/?do=findComment&comment=3393339

Cannot load texture c:\users\ackermann\appdata\local\arma 3\squads\afoo\x9qxe9onzq.paa.

that looks like the path is looked up lowercase

Unit emblem name

Ld1xlv7AoB.png

(from avatar image on website, haven't checked ingame)
seems to be non-lowercase, that its probably the cause for the problems.

Confirmed on my linux server
Unit: https://units.arma3.com/unit/wolfcorps
If you "show image" on the avatar, you get https://units.arma3.com/groups/img/3666/WbGwmxkqXv.png
-> WbGwmxkqXv.png
on my server I have /home/wolf/.local/share/Arma 3/squads/Wolf Corps/WbGwmxkqXv.paa
log spam on windows client: Cannot load texture c:\users\dedmen\appdata\local\arma 3\squads\wolf corps\WbGwmxkqXv.paa.
I assume the linux server can't find the texture as it looks it up in lowercase, and thus doesn't transmit to client.

test to confirm that would be to make a squad.xml where the logo filename is not lowercase. which should then also break.
or to manually lowercase the filename on the server, such that arma will be able to find it.

Second confirmation.
When arma does a lookup on the squad path, it does a "tolower" on the path before looking it up, which will make the lookup fail on linux.

Fix is in dedmen->KK discord DM https://discordapp.com/channels/@me/651095233513127946/669155705072386088

alternative fix could be done on arma units backend, to only pass lowercase logo filename, but then the same issue would persist with squad.xml

Fix in performance/profiling 146434 and next dev branch