Gov't lawfag here.
No, there is no statute of limitations issue. It's not a criminal statute. It's a requirement and, if not intentionally ignored, doesn't have a real remedy unless either Congress/President decides to reallocate money over it, or the Pres fires someone. A lot of times it's a no autopsy-no foul situation.
Ratcliffe isn't doing this intentionally, he's trying to expose DS rats, so no harm to him.
One last thing - the report is not required in 45 days. An assessment is required, and technically he's probably already delivered it publicly/privately. The report is due 45 days after that. Read the EO closely.