Live View FlexiZone Single AF ignores selected point (Canon EOS 5D Mark IV)

I’m having a persistent issue with Live View autofocus on my Canon EOS 5D Mark IV when shooting tiny flowers in awkward camera positions using FlexiZone Single AF.

Situation / workflow:

• Touch Shutter is OFF, but I still tap the screen to select the focusing point.
• AEB (Auto Exposure Bracketing) is ON: I want multiple bracketed shots per trigger.
• The camera is often held at odd angles, making viewfinder use difficult.
• Manual focus is impractical even with magnified Live View.

Problem:

• After tapping a focus point, half-pressing the shutter causes the camera to refocus, ignoring the point I just selected. (Touching the shutter first locks out tap to focus.)
• As a result, shots of very small subjects are frequently out of focus, even when I try to control AF precisely.

Settings:

• AF Method: FlexiZone Single
• AF Operation: One-Shot AF
• Touch Shutter: Disabled (enabling it would prevent the camera from reselecting a focus area, but it does not automatically cycle through all shots in the desired AEB sequence)
• Orientation-linked AF point / Continuous AF / Servo AF: reviewed or not applicable
• Display overlays / Quick Control toggles: adjusted, issue persists

Camera / lens info:

• Canon EOS 5D Mark IV
• Firmware: 1.4.0
• Lens: 100 mm f/2.8L Macro IS USM

Question:
Has anyone else encountered this? Is there a way to make Live View AF reliably lock to a touch or predefined point while using AEB for small subjects in awkward positions?