Yes. City have applied to the CAS seeking a ruling that the decision of UEFA's Investigatory Chamber to refer the matter to the Adjudicatory Chamber should be set aside on the grounds that the referral was procedurally flawed. The CAS has accepted the application and the arbitral process is going forward in the usual way. IIRC (no time to check), the CAS has reportedly clarified that UEFA's Adjudicatory Chamber can proceed notwithstanding that the arbitral process with respect to the Investigatory Chamber's referral is ongoing.
That will have no bearing on the progress of the CAS case. They'll decide whether the Investigatory Chamber's referral should be struck down owing to procedural flaws when the case reaches the appropriate stage, irrespective of whether or not the Adjudicatory Chamber has by then decided what to do about MCFC.
The established position is that the CAS will usually consider the possibility of appealing against a decision of the Adjudicatory Chamber to be a sufficient safeguard of the appellant's interests and will thus intervene based on procedural factors only when the ultimate appeal isn't a sufficient safeguard of those interests. And David Conn claimed that City are likely to fail based on a precedent where the CAS declined to strike down an award against AC Milan for procedural reasons, stating that Milan's interests were sufficiently safeguarded by the opportunity to raise the procedural issues in any subsequent appeal against the Adjudicatory Chamber's decision.
IMO, whether this would apply to City may not be as clear-cut as Conn supposes. I've read the full Milan ruling and it relates to a set of facts that differ from City's in a number of material respects. Moreover, in that ruling, the CAS reiterated its willingness to intervene on procedural grounds where necessary. Nonetheless, it's true that the latter situation is going to be an exception rather than the rule.
However, the bottom line is that anyone looking from outside - whether David Conn, me or anyone else - is guessing. The information currently in the public domain isn't adequate to allow us to form a properly considered view.