If I change the stack size or multiplier of something, the Logistics tab (In my Inventory) is completely cleared when I reload a save game.
It doesn't seem to happen if I load an old game. Only if I save a game, exit the game, change stack size, and reload the same game.
This is really strange. I wonder if this is a bug in Factorio.

Edit: I believe it is a bug in Factorio and not your mod. I changed the stack size in the data-final-fixes.lua of one of my mods and this reset and cleared the Logistics tab in my Inventory. I'll check the forums later to see if this is a known bug.
Edit again: Ok, sorry for this. It's not your mod. FYI: I also found that removing or adding a mod seems to cause the reset.

Interesting, thank you for reporting this.

Found what the problem was. The SchallUraniumProcessing mod. In Control.lua it resets technology effects for everything in the game.
I renamed Control.lua to Control.lua.txt and this eliminated this issue.
Also noted that someone complained about one of Bob's mod doing this.
This is extremely poor programming practice. Only items affected by the mod should be changed.

Control.lua code:
local function reset_tech_effects()
for index, force in pairs(game.forces) do
--begin
force.reset_technology_effects()
end
end
local function configuration_changed()
reset_tech_effects()
end
script.on_configuration_changed(configuration_changed)

Nice, I appreciate a good "bug hunt". In my experience, seemingly random mods can reset technology effects. For some quality-of-life mods / scenarios, I had to change how force bonuses/nerfs were applied (they tend to just SET force bonuses, instead of modifying relatively). If you're having any issues with some quality-of-life mods or weird interactions with technology resets, I'd be glad to help you.

Thanks. Doing this helps me understand LUA better. I am mostly a C,C++, and machine code programmer. LUA is extremely frustrating.