This matter has bugged me a lot with the Photo sharing. For some apps the limit is 1 for others it's 5,10,20 but for others 40+ photos are fine. In my case with my 5s/SE and the latest official iOS10 version I can use:
* Apple Mail app, Gmail, Email by Easylido, Spark, Airmail, Telegram, Messenger - 40+ photos
* Facebook - maximum 30
* Apple (i)Message app - maximum 20
* WhatsApp -
was maximum 30 (since 23-1-2017, was previously 10)
but again 10 with iOS10.3.1 and latest app version (1-5-2017)
* Google Drive - maximum 10
* Dropbox - maximum 1 - solution is using Workflow though with
this
I don't get it. It seems that the developers need to build this in. Especially for WhatsApp I have to split it up now. Although I'm now looking into
Workflow app if there is one for them as well. Like I use to export multiple photos to a specific Dropbox folder.