From time to time, it happens more or one of the following:

-The categories "EVA items" and "Containers" are empty in VAB, though I can access the seats inventories in the command pods. The items belonging to those categories, however, are found in the "utilities" and "payload" categories.
-The categories "EVA items" and "containers" are duplicated in the VAB category list.
-Although the seats inventories in the command pods are available in VAB, when launching, I cannot acces the kerbal's inventories in EVA. Right-clicking on them has no "inventory" button. There's no "inventory" buttons on the command pods either. Neither do TAB keys or others such as "g" work. When approaching a container and right clicking, the button "inventory" appears but nothing happens on click.

My modulemanager is 2,8,1

This ksp.log is from a situation in which the second and third items are happening.

KSP.log.zip

I've checked the log and didn't found any error related to KIS. Moreover, the records in the log indicate a normal KIS work.

However, I see a major problem in your mods setup. There are at least three mods that failed to load properly: AnomalySurveyor, ToadicusTools, and TweakableDeployablePanels. Once the game is loaded, the log becomes flooded with critical errors from various modules. E.g.:

[ERR 07:10:16.043] Module DMSeismicSensor threw during OnStart: System.NullReferenceException: Object reference not set to an instance of an object
  at DMagic.Part_Modules.DMBasicScienceModule.findContainers () [0x00000] in <filename unknown>:0 
  at DMagic.Part_Modules.DMBasicScienceModule.OnStart (StartState state) [0x00000] in <filename unknown>:0 
  at DMagic.Part_Modules.DMSeismicSensor.OnStart (StartState state) [0x00000] in <filename unknown>:0 
  at Part.ModulesOnStart () [0x00000] in <filename unknown>:0 

or an endless serie of:

[EXC 07:10:48.309] NullReferenceException
	Kopernicus.RuntimeUtility.LateUpdate ()
[EXC 07:10:48.312] NullReferenceException
	Kopernicus.Components.KopernicusStar.<Awake>b__10_1 (UnityEngine.Camera cam)
	UnityEngine.Camera.FireOnPreCull (UnityEngine.Camera cam)

etc.

That said, even if there is a problem in KIS, it's impossible to locate it until the other issues are fixed. You may try removing the failing mods and test if the issue is still there.

Thanks for your thoroughness! I'll report if hte issue happens again without those other mods.

Closing it for now. feel free to reopen if the issue comes back.