Series not updated when transferred to kobo

hello everybody.

I have noticed a strange behavior with my kobo for the last 3 or 4 last calibre updates/plugin (?) :
when I am transferring a book (from a collection) to my kobo, the series are not immediately updated (ie blank information on the kobo series field). I have to disconnect my kobo, reconnect it and then update the metadata from the koboUtilities menu (rev2.9.0). It has been previously working nicely for years .
I am using calibre 4.7 with Kobo clara HD running 4.18.13737

Is this normal or am I doing something wrong ?

Thanks
Jacques