32-bit PNGs disappear from the program monitor when animating their positions

Steps to reproduce:

1. Import a 32-bit PNG image with alpha.

2. Drag the image onto the timeline.

3. In the Effect Controls panel, click the clock icon next to "Position" to set a keyframe.

4. Click and drag on either the X or Y position values.

Expected: i should see the image moving left/right or up/down in the program monitor

Actual: The image vanishes from the program monitor while the position values are being adjusted, and reappears when i release my mouse button. This makes it extremely difficult to position the image, as i have to guess where it is, and then release the button to see if i'm correct.

i don't know if this happens only with 32-bit images, or only when animating Position, but these steps are 100% reproducible on multiple systems, and the bug has been in the software for at least the last 5 years.