This is a nasty problem and becoming all too common as carrier frequencies go up.
Maybe a little primer on drive noise types is in order.
The first type is high frequency components in the current on the incoming power leads. These result from the drive input rectifiers using the current non-linearly to keep the DC bus charged up. Reactors in the input power leads or, in some cases, a DC bus choke reduce this source of noise. In extreme cases, a matrix filter may be used or alternatively, a more complex input rectifier with twelve or eighteen diodes (pulses) and a phase shifting input transformer.
The second source is radiated RFI/EMI mostly from the motor leads. This comes from the high frequency components in the sharp pulses that the drive sends to the motor (carrier pulses). The solution here is to put the motor in conduit or, as is often done in Europe, use shielded motor leads.
The third source is a really bad actor---common mode noise. It is caused by the capacitance between the motor leads and ground. The high frequency components couple thru the capacitance to ground and then must find a way back to the DC bus of the drive. The most likely way is to travel thru ground all the way back to the substation transformer secondary and then thru the AC supply back to the drive. This clearly puts high frequency noise in the ground system and also in the AC power leads. Noise problems can surface long distances from the drive and in a completely random arrangement. Any instrumentation depending on this ground system or AC power can be affected. Note also that the attempts to deal with noise source number two above make this third noise source worse. The only drive solution that I have seen work is a drive isolation transformer with a grounded wye secondary. This allows the high frequency ground currents to travel back to the DC bus via a shortcut and stay out of the rest of the network. Unfortunately, at higher horsepowers, an isolation transformer can be a big expense.
I have had some success in situations where only one instrumentation device is having a problem by dealing with the instrument rather than the drive. This is particularly desireable if the drive hp is high.
The first general rule is not to ground to earth anything on the instrumentation if that is possible. Bring all shields etc back to instrument common but don't tie the common to earth. Another thing that works sometimes is to use a high performance noise filter on the power supply to the instrument. Often this is 120VAC and the filter can be quite inexpensive. I've even put a small UPS with good input/output isolation in the power supply to the instrument with good results.
The bad news is that there seems to be no systematic way to deal with noise problems. I just hate the stab-in-the-dark method but haven't found anything else that does any better. Drive noise problems keep many consultants employed, some with good track records and some not so good.
Good luck. I'm glad I'm not there!