@Tom Raddatz, I have a portfolio of Section 8 properties in the St. Louis area. I love the niche, it's all I do.
I'm assuming the verbiage is coming from the HAP contract, which should be the same for all HA's but I can't find that phrase in mine.
In any case, I've never had a problem getting rent from the HA. I have had an instance where the tenant didn't send in the required paperwork at renewal (the tenants have to do a re-certification each year where they send in house occupant info and updated income info) and the HA held up payment until it was received. In that time, the Housing Authority told me that the tenant was responsible for the payments until the tenant sent in the paperwork). I helped the tenant get the required paperwork sent in and the HA made up all the back rent.
The biggest opportunities for issues arise around changes, in my experience. New tenants, rent increases and tenant/HAP portion changes at renewal are when things get missed and the payments can be wrong, delayed, etc. But they're always fixed in the end, it just requires systems & diligence on my part to make sure everything is being paid as it should be.
Regarding the MtM lease, Section 8 requires that the initial lease term must be for 1 year. It can go to MtM after the first year but I just keep mine on annual leases that correspond with the tenant's annual recertification/renewal. I do this because I think it stabilizes my portfolio to some degree & we can submit rent increases 90 days prior to renewal to the Housing Authority. By keeping the leases annual, my PM software reminds me when to submit those increases. I might go with MtM if I didn't have Section 8 tenants and I was worried about payment. But I'm not (I'm currently owed $0 in past due rent - the HA and my tenants are all paying).
Section 8 is a great way to go if you screen thoroughly and learn/master the processes of your local PHA. Good luck and let me know if I can help further!