Hello again. Encountered an error while using cam mode.
When i watched at some ammo moving on belt - after it went to loader and then to chest - got error. Text (traceback):

Error while running event item-cam-2::on_object_destroyed (ID 174)
item-cam-2/script/focus-update.lua:81: attempt to call field '?' (a nil value)
stack traceback:
item-cam-2/script/focus-update.lua:81: in function 'fn'
item-cam-2/script/focus-update.lua:533: in function 'apply_fn'
item-cam-2/script/focus-update.lua:556: in function 'tick'
item-cam-2/script/focus-behavior.lua:220: in function 'update'
item-cam-2/script/events-tick.lua:59: in function 'tick_one_focus'
item-cam-2/script/events-tick.lua:75: in function <item-cam-2/script/events-tick.lua:71>
Loader and item was from Krastorio2, chest was from AAI containers.

Same happens with any item (vaniilla and modded) goes to chest with loader. If it is just inserter to chest - all works perfectly. If item is moving from chest to belt - result differs. If inserter is used - cam mode works as planned. But if loader is used - there is no exception, but i exit from cam mode automatically.
Mod version 0.9.0, game version 2.0.55

Thank you for the report. I forgot that internally there's 2 types of loaders - a 1x2 and 1x1 variant - and code only accounts for the 1x2 variant. K2's loaders are 1x1s and I reproduced crashing when cam needs to switch out of loader, and cam staring at any container with a 1x1 output loader present. I think this was what you were running into.
It's now fixed in 0.9.1.

I wasnt able to produce base game loaders not working -- if that or something else is still an issue, I'll probably need a save to try reproducing onto

Nah, as i mentioned it was k2 loaders. Btw iirc - recently i saw a mod that adds crane to load/unload trains. I dont use it, but depend on how it is made - maybe it also can crash cam mode. Searched them now and found a bunch of different cranes and yes they are just big loaders. 3x1, 3x2, 6x1, 6x2 sizes if it helps you somehow.