GTRPaul,
You will want to start by making sure the Glyph Drive is connected to the Mixer's second FW port and not directly to the Mac [ and the mixer connected directly to the Mac ]. This will make sure that you are not drawing too much power from the Mac via the FW port(s); which can result in lost data packets and dropouts ( when using certain interfaces ).
Next, you will want to check your BitDepth and Block Size; when recording at higher Sampling Rates, you are recording quite a bit more dynamic audio information. If your Block Size is set super low, you are really pushing your computer. Start by bringing the block size up to 64( and test ) and then up to 128 ( and test ) to see if the pops and clicks are no longer present.
Additionally, Apple recommends that when recording audio; that you record directly to an external HD [ with a minimum 7200 RPM spinning speed ].
**Should Studio One be installed on your external HD, [ and being run off the external HD], while you are also recording to the same drive data packet loss can occur as well as sluggish operation of the recording software.