[appmus]

You get latency or you get an actual echo (like a reverb?)
{ is not a reverb echo no effects in signal path dry as a bone}
{when I select analog 1 from focus-rite only vocal is straight no latency}


How are you monitoring/listening when tracking?
{using the headphone jack only of the focus-rite}
{ HP 01 and HP 02 – connect one or two pairs of stereo headphones at the two ¼” (6.25 mm) TRS jack sockets below the controls. The headphone outputs always carry the signals that are currently routed to analogue outputs 1 & 2 and 3 & 4 respectively (as stereo pairs) in Scarlett
MixControl.}

What exact headphones?
{beyerdynamic DT770 PPO 80 OHM}
Open back headphones may create more of a challenge for yourself. And in some cases when used close to the mic actually cause an echo sound or feedback.

What exact microphone plugged in where?
{Sure SM48S plugged into Input 1 – using XLR input sockets

What latency are you getting at those small IO Buffer size setting. You can estimate that by recording a click track. and measuring the latency between the click track and audio track. (direct record the click track inside Pro Tools can make it easier to measure between matching clicks)

{will have to work on that}

Can you record using hardware monitoring through the Scarlet?
{mute monitor outputs 1&2 on Scarlet.
Set Line output 3&4 to mono.
select analog 1 (mic input) for output 3
select Playback (DAW)1 for output 4.

I can record but only mono vocal in left side daw playback in right side}

As you increase the IO Buffer size do you get a fairly linear/expected consistent increase in latency.
{yes}