@Prabha22 the reason why May-dec 2018 applications got delayed is because IRCC was not prepared for the volume of invitations they gave out until they realized it was a mistake and tried to regulate on the number of invitations given out..
Right now they are trying to keep up to maintaining a 6-8 months processing time with the 2019 apps and trying to catch up to 2018 backlogs..
It is sad but it is the fact - with the current trends - its taking almost 11 - 13 months for them to process the 2018 backlogs - especially around med expiration - that is when they start picking up backlog files ..