A quick Google search for 'playstore downloads on roaming data' will bring up a dozen odd search results, many pointing to Google's official product help pages.
This appears to be a Nougat related issue ( bug?) that's been reported from across devices and networks. Doesn't seem to be specific to CM.
The way I've managed to get around it (only to a reasonable extent) is by downloading updated apps from APKmirror and similar sites (PLEASE BE VERY CAREFUL WHERE YOU DOWNLOAD FROM). As for downloads originating from chrome or Android webview/chromium webview, download manager not downloading links got solved by using ADM wherever I could. Though I feel using another browser with a built in download manager could also be given a shot.
I'll check back to see if there are other workarounds mentioned on here, though can't wait for Google to fix things back up.
Sent from my Google Pixel XL using XDA Labs
---------- Post added at 08:47 AM ---------- Previous post was at 08:44 AM ----------
Are you saying you are able to download from the play store on a roaming data connection? Well it doesn't seem to work on stock 7.1 Roms on the Nexus. Maybe it's changed in cm14.1. Can't test roaming cause I'm home.
Unfortunately it hasn't, can't download on roaming data on CM based RR 5.8.0. From Google's official product forums and from what I've picked up on Xda as well, this appears to be a Nougat specific issue, probably the latest update (7.1.1) given that's around when users started noticing the bug.
Hope things can go back to using playstore as we've always done soon enough
Sent from my Google Pixel XL using XDA Labs