DAU understands the question to be the following worded problem statement – Subject to the unit type stated in the CLIN, are there restrictions in what unit type (e.g., Each, Lot, Month) can be used in the CLIN and can there be issues when DFAS makes progress payments against such CLIN(s)?  

As to restrictions in the choice of Unit type used in CLIN that is to be subject to progress payments, the first concern would be to ensure Lot is the appropriate unit type chosen for the deliverable. See that this is iaw DFARS 204.7103-1(g).

It is true that the PCO can utilize a combination of types of CLINs (FAR 32.113(h) and PCO is required to convey payment instructions in Section G of the Contract iaw DFARS PGI 204.7108. 

FAR 32.113(h) states -  

 “Financing of contracts for supplies or services through any appropriate combination of advance payments, guaranteed loans, and either performance-based payments or progress payments (but not both) in accordance with their respective subparts.” 

Also note DCMA-MAN 2101-02, February 14, 2019 SECTION 9: PROGRESS PAYMENTS BASED ON COST 9.1. REVIEW OF PROGRESS PAYMENT CONTRACT/DELIVERY ORDER REQUIREMENTS. link - https://www.dcma.mil/Portals/31/Documents/Policy/DCMA-MAN-2101-02.pdf?ver=2019-02-20-154800-810 

Which states ….“The ACO should confirm the PCO provided distribution/payment instructions and ensure they are included in Section G of all contracts containing the progress payment clause. The distribution/payment instructions must comply with the requirements of DFARS PGI 204.7108.”