Yeah same thing is happening with me. Got my PPR in june 2018, added my wife soon after and submitted her docs in July 2018. Application was being processed in Ottawa office all along. Seeing my application stuck in ‘additional documents being reviewed’ for a long time, called them in December and found out that application has been transferred to Singapore visa office.
Mailed singapore office and they claim that they received it in end Nov 2018 only and have placed it in queue for processing, basically implying that they are treating it like a new application.
Absolutely no clarity why they put it on hold for 4 months and then suddenly transferred it. The wait seems to be endless!