How to Tell Whether the Blink Is Working (Quick Visual Test)

Do a controlled test

Before blaming the pack, rule out everything else. Disable all other resource packs so only this one is selected, then press F3+T to reload textures. This removes any chance that another pack is supplying the Eye of Ender or Heart of the Sea texture. With a clean setup, any animation you see is definitely coming from this pack.

Watch the right thing

Get the item on screen and keep it still. For the Eye of Ender, hold it in your main hand and press F5 for third-person view, or drop it and stand a few blocks back. For the Heart of the Sea, an item frame on a wall is the easiest way to watch it for a while. A working blink shows the eye or the heart opening and closing on a repeating loop. A broken or overridden texture stays completely frozen with no change over several seconds.

Interpret the result

If it blinks with only this pack on, the pack works and your earlier problem was a load-order conflict, so re-enable your other packs and move this one above them. If it does not blink even alone, check that the pack is actually in the Selected column and not just the Available column, then reload again with F3+T. Confirm you are looking at the plain item and not a renamed or special variant another pack might handle differently.