Preposition and case

Here's an interesting sentence: Při akutním onemocnění včetně nachlazení, rýmě, oparu na rtu apod. nebo z jiných důvodů, které nedovolí uskutečnit plánovaný výkon, nám laskavě tuto skutečnost sdělte na XXX.

The preposition včetně always requires the genitive, but here you have the word in bold in the dative or locative. I guess such an error arose owing to the preposition při at the beginning of the sentence, which does need locative, but that preposition modifies only akutním onemocněním and not the rest of the sentence. What also surprises me a little is how a preposition in such a distance can still influence a term that it doesn't refer to. It could also be argued that the fact that both nachlazení and opar have the same ending in the dative, genitive and locative could have played a role here, but this is something of which I'm still not certain.