Hi
I've just looked up some information on this train, both via NS International (Dutch) and SNCF websites.
If you go to the SNCF website, select on the left "Horaires & Info trafic en temps réel", then Rechercher "Un Train", type 4850 and select your date, you'll be able to find it's running normally (here at least).
Ticket sales should open up 3 months in advance, however, the engineering works aren't that far ahead visible to the public. If you look here
http://aide.voyages-sncf.com/toute-...oraires-trafic-gares/perturbations-et-travaux you can see that on the 10th of this month, they uploaded all the works for July. So maybe they already 'know' works might happen, so the train isn't fully advertised/sold yet. Further information on this, I sadly can't give you (yet), as I don't know what'll happen for August.