Hl7 5.1 mentions that <lotNumberText> is a SHOULD condition and says below:

"lotNumberText should be included if known. It may not be known for historical immunizations, planned immunizations, or refused/deferred immunizations. b. This manufacturedMaterial SHOULD contain zero or one [0..1] lotNumberText (CONF:1098-9014)"

Since its a should condition, per our understanding we can skip the tag if value is not known. But Cypress is failing patient file without this tag. Please look into this; I tried CMS127 - 12_Doris_Barker patient file.