Thanks Chantelle, Jim Fogle, rharv, I appreciate the help:

My version of PTP is Version 2018 (2).

Chantelle:
Under 'Options, Preferences, [Tab] 2-Audio:
The Driver Type had 3 options listed, 'Windows Audio', 'MME' and 'ASIO'.
There are no ASIO drivers installed on my system.

The [As Found] settings were 'Windows Audio' of which the input and output drivers listed had only one choice each: Input - Microphone (2-USB Audio Codec) and Output - Speaker/Headphone (Realtek(R) Audio).
I switched to 'MME' and tried combinations of the Inputs [Microsoft Sound Mapper / Microphone (2-USB Audio Codec)] and Outputs [Microsoft Sound Mapper / Speaker/Headphone (Realtek(R) Audio)].

In all cases I end up with being able to playback track 1 (an *.mp3 file), but no signal shows on the track 2 mixer or sound plays when I try to record a guitar mono track onto track 2.
-My signal levels on my Yamaha Audiogram6 interface show as working
-Track 2 has been selected (shows red) and the mute is off (green P)
-The 'In' levels on the Tracks window (bottom right) show the guitar signal (only while recording) is being picked up
-The 'Out' levels on the track window (bottom right) show the signal from track 1 playback, either in play or record mode.

I have returned to [As Found] settings.

Jim Fogle: For the Audio Interface you mentioned, I wasn't sure if you meant the sound card or the outboard USB interface, but the Yamaha USB Audio Interface has a mono/stereo switch and a mic/line switch on channels 1 and 2. Channels 3 and 4 have L + R 1/4" phono jack line inputs (L - mono) and have no switches .

I am using input 2 on the Yamaha: inst / mono switched and the signal leds are showing when I play. The signal is getting to the PTP program 'In' meters , so it seems like the USB interface is working and driving into the PTP program. On the Yamaha, I tried switching mono to stereo and also trying channel 3; same, no signal getting to channel 2 (actually using channel 3 gave a much lower signal than channel 2, channel 3 must have a lower gain for accommodating proper line inputs). When switching the PTP Channel 2 to stereo, I got no input into PTP at all, possibly because the Yamaha channel 1 wasn't being used, not sure.
I returned my guitar pedal output to channel 2 of the Yamaha and left the switches as 'mono' and 'inst'. I returned the PTP channel 2 to mono audio.

rharv: Right clicking on the track to check the 'Port Setting':

I checked the Port setting; there was only one choice - Speaker/Headphone (Realtek(R) Audio), but below the 'Port' setting was 'Set all Audio Tracks to Speaker/Headphone (Realtek(R) Audio), which I did. So all the tracks should be routed to the same port.
I still have the same issue, I can only playback track 1 and no signal is getting to track 2 when recording on track 2.