Just for everyone’s information - I’m on a Mac and am experiencing no odd behavior.
Here are the steps I used to change the whole note tied to eighth note tied to 16th note to the desired note values using force duration. Remember that you do not need to delete anything, just over-write the notes with Force Duration.
On my laptop without a MIDI keyboard:
• Click on the tied note (this selects the entire tied note, no need to use marquee)
• Type the letter O (to turn on Force Duration)
• Push Enter (to get into Note entry mode at the desired position)
• Type 6 and period (for dotted quarter note)
• Type Shift-option A (writes dotted quarter A at correct octave)
• T (to tie)
• Type 7 and period (for dotted half note)
• A (writes dotted half note A)
• T (to tie)
• Type 4 (for sixteenth note)
• A (writes 16th note A)
• Type the letter O (to turn off Force Duration)
• Escape Key (to end editing session)