I'm using AF-C with back button focus with a single AF point. The Kingfisher shots are a complete mystery to me, shot at 400ISO while resting on the ledge of the hide, focus point is on the birds head, but nothing is in focus and it's noisy for 400ISO.
Here's a 100% crop, taken from the original in LR, using the "Edit In" function & PS, so there are minimal changes to the original.
View attachment 258969
Like I say, I have used the T2 with the 100-400 & 1.4TC extensively with very good results, so I'm convinced I must have something else in the set up wrong. However, my landscapes & portraits seem fine.