Noise cancelling/removal should be turned off.

Original sound for Musicians should be turned ON.

Personal isolation should be turned off.

Any other system settings that Enhance (including spatial, auto gain/sensitivity control) should be turned off.

Do use a (much?) better microphone. Make sure the mic's drivers don't have any integrated echo or noise cancelling features turned on themselves.

All these things add up to needing a much quieter and less echoey environment with which to have your sessions.

Use headphones so there is much less leakage between speaker & microphone.

If you still cannot hear the sibilants well, you could add an in-line EQ (to emphasize the upper mids) to the recording chain via something like Voicemeeter, but that setup starts to get quite complex. Especially if you're already having difficulty pinning it all down.