It sounds to me like insufficient neck relief. Have you checked that you have tangible relief on those strings? Hold down the string on the 1st fret and the 15th and then tap the string at the 6th fret. There should be a small but perceptible gap. If the string’s hard down on the fret, then there is insufficient relief.
With a Rick, there are particular techniques to adjusting them so, if the above is the case and if you aren’t familiar with them, best to report back here before doing anything yourself 🙂