In our project we are creating custom list definition and list instance based on that definition, as follows:
Elements.XML in List Definition:
<ListTemplate
Name="MyListsDef"
Type="10000"
BaseType="1"
OnQuickLaunch="TRUE"
SecurityBits="11"
Sequence="110"
DisplayName="MyListsDef"
Description="My List Definition"
Image="/_layouts/15/images/itdl.png"
DocumentTemplate="121"/>
Lists are created based on that List Definition, during site provisioning, see List Type that matches ListTemplate Type (onet.xml block is below)
<List Title="My Library" Type="10000" FeatureId="{GUID}" Url="Lists/MyLibrary" />
However, when sites are provisioned, those libraries don't have "Sync" option available in the Toolbar and cannot be synced offline, although they have property "EnableOfflineSync" set to TRUE in Advanced List Settings. (When we create Document Libraries based on the OOTB Doc Lib template, they have "Sync" button available in the toolbar.)
What could be the reason for that? Any helpis welcome.
Thanks
Dragan