Here's what I did:
Stopped Resilio Sync.
Rotated /usr/local/resiliosync/var/sync.log (which had grown to 66MB in a couple days).
Started Resilio Sync, and allowed it to discover peers.
Created a test file via 'touch /volume1/Apps/Sync/General/test-file' (General is one of my synced folders). Confirmed nothing appeared on other hosts.
Stopped Resilio Sync. Made a copy of the log (attached as 'sync-1.log'); rotated logfile.
Started Resilio Sync, allowed it to discover peers and transfer the test file, which is does on initial launch.
Stopped Resilio Sync. Made a copy of the log (attached as 'sync-2.log'); rotated logfile.
Verified ACL/permission access:
jochs@Synology ~ $ sudo synoacltool -get-perm /volume1/Apps/Sync/General/ rslsync
ACL version: 1
Archive: is_inherit,is_support_ACL
Owner: [jochs(user)]
---------------------
[0] user:jochs:allow:rwxpdDaARWc--:fd-- (level:2)
[1] user:rslsync:allow:rwxpdDaARWc--:fd-- (level:2)
[2] user:guest:allow:rwxpdDaARWc--:fd-- (level:2)
[3] user:admin:allow:rwxpdDaARWc--:fd-- (level:2)
[4] user:transmission:allow:rwxpdDaARWc--:fd-- (level:2)
====================================================
User/Group: [rslsync/users,administrators,sc-download,rslsync]
Final permission: [rwxpdDaARWc--]
The first time Sync sees the test file is in 'sync-2.log', line 1744 (i.e., only after starting fresh and scanning its folders). I can provide whatever additional logs, details, and tests are needed.