Kerbal Space Program

I was going to file a similar report but I'll flesh this one out as I'm pretty sure they are related. A more complete title would perhaps be "Opening PAW can cause initially placed parts to be picked up and / or disappear". This interaction for the reproduction below also causes flag meshes to disappear and could potentially be causing other functions to break.

Steps for reproduction:

1) Enter SPH, place MK1 Inline cockpit.
2) Right click on part, PAW opens, part is picked up.
3) Mouse over PAW, part disappears.
4) Move mouse away from PAW, part is under mouse cursor.
5) Place it down, flag is missing.
6) Toggle flag in PAW becomes inoperative.
7) Start a new craft.
8) Place MK1 Inline cockpit again.
9) Right click, PAW opens, part remains in place.
10) Mouse over PAW, part disappears.
11) Mouse away from PAW, part has been picked up and is under the cursor.
12) Place part, flag is missing and toggle inop.
13) Start a new craft.
14) Place Stayputnik.
15) Right click part, PAW opens, part remains.
16) Mouse over PAW, part disappears.
17) Mouse away from PAW, part reappears but as placed, not under mouse cursor.

Similar behaviour can be seen with other parts when initially placed or otherwise but I'm fairly sure this process with these parts is 100% repeatable and covers the majority of the seemingly interlinked issues I've noticed. For example, flag meshes don't always disappear on parts that otherwise behave similarly when initially placed and right clicked.

Confirmed, same happens to me with various parts that can be used as root part. Command pods, probe cores, some fuel tanks (mostly those with reflective texture), reaction wheels, structural parts, I didn't look further. No mods, clear game, 1.12.1 + DLCs