C_Container.GetContainerNumSlots(5) still returns the number of slots of the Reagent bag.
C_Container.GetContainerItemID(5, [slot]) now returns empty.
C_Container.GetContainerItemLink(5, [slot]) now returns empty.
Is there a workaround for this or a different command now?
Also, is there a place where the breaking changes of 10.2.6 are being discussed somewhere?
https://warcraft.wiki.gg/wiki/Patch_10.2.6/API_changes
https://warcraft.wiki.gg/wiki/World_of_Warcraft_API
Though, at this time, they appear to be lacking specifics.
[added]
I’m not seeing any changes to those functions
https://github.com/Gethe/wow-ui-source/blob/live/Interface/AddOns/Blizzard_APIDocumentationGenerated/ContainerDocumentation.lua#L154
https://github.com/Gethe/wow-ui-source/blob/live/Interface/AddOns/Blizzard_APIDocumentationGenerated/ContainerDocumentation.lua#L184
The old bankitems addon still seems to be able to read the reagent bag without problem. Perhaps you can peruse the code and see if they used a different method?