diff --git a/chrome/content/zotero/xpcom/sync/syncRunner.js b/chrome/content/zotero/xpcom/sync/syncRunner.js
index cbd098a7f..e0d3f99ee 100644
--- a/chrome/content/zotero/xpcom/sync/syncRunner.js
+++ b/chrome/content/zotero/xpcom/sync/syncRunner.js
@@ -371,8 +371,10 @@ Zotero.Sync.Runner_Module = function (options = {}) {
 			}
 			
 			let remoteGroupVersions = yield client.getGroupVersions(keyInfo.userID);
+			Zotero.debug(remoteGroupVersions);
 			let remoteGroupIDs = Object.keys(remoteGroupVersions).map(id => parseInt(id));
 			let skippedGroups = Zotero.Sync.Data.Local.getSkippedGroups();
+			Zotero.debug(skippedGroups);
 			
 			// Remove skipped groups
 			if (syncAllLibraries) {
@@ -390,10 +392,12 @@ Zotero.Sync.Runner_Module = function (options = {}) {
 					// If syncing all libraries, mark any that don't exist, are outdated, or are
 					// archived locally for update. Group is added to the library list after downloading.
 					if (!group || group.version < remoteGroupVersions[id] || group.archived) {
+						Zotero.debug(`Marking group ${id} to download`);
 						groupsToDownload.push(id);
 					}
 					// If not outdated, just add to library list
 					else {
+						Zotero.debug(`Adding group library ${group.libraryID} to sync`);
 						libraries.push(group.libraryID);
 					}
 				}
@@ -425,6 +429,8 @@ Zotero.Sync.Runner_Module = function (options = {}) {
 					.filter(id => Zotero.Libraries.get(id).libraryType == 'group')
 					.map(id => Zotero.Groups.getGroupIDFromLibraryID(id))
 			}
+			Zotero.debug("Local groups:");
+			Zotero.debug(localGroups);
 			remotelyMissingGroups = Zotero.Utilities.arrayDiff(localGroups, remoteGroupIDs)
 				.map(id => Zotero.Groups.get(id));
 		}
@@ -547,6 +553,8 @@ Zotero.Sync.Runner_Module = function (options = {}) {
 		}
 		
 		// Note: If any non-group library types become archivable, they'll need to be unarchived here.
+		Zotero.debug("Final libraries to sync:");
+		Zotero.debug(libraries);
 		
 		return [...new Set(libraries)];
 	});