diff --git a/copyparty/__main__.py b/copyparty/__main__.py
index 64a36145..d1a83ff2 100755
--- a/copyparty/__main__.py
+++ b/copyparty/__main__.py
@@ -956,7 +956,7 @@ def add_auth(ap):
     ap2 = ap.add_argument_group('IdP / identity provider / user authentication options')
     ap2.add_argument("--idp-h-usr", metavar="HN", type=u, default="", help="bypass the copyparty authentication checks and assume the request-header \033[33mHN\033[0m contains the username of the requesting user (for use with authentik/oauth/...)\n\033[1;31mWARNING:\033[0m if you enable this, make sure clients are unable to specify this header themselves; must be washed away and replaced by a reverse-proxy")
     ap2.add_argument("--idp-h-grp", metavar="HN", type=u, default="", help="assume the request-header \033[33mHN\033[0m contains the groupname of the requesting user; can be referenced in config files for group-based access control")
-    ap2.add_argument("--idp-h-sep", metavar="RE", type=u, default="|:;+,", help="if there are multiple groups in \033[33m--idp-h-grp\033[0m, they are separated by one of the characters in \033[33mRE\033[0m")
+    ap2.add_argument("--idp-gsep", metavar="RE", type=u, default="|:;+,", help="if there are multiple groups in \033[33m--idp-h-grp\033[0m, they are separated by one of the characters in \033[33mRE\033[0m")
 
 
 def add_zeroconf(ap):
@@ -1438,6 +1438,7 @@ def main(argv: Optional[list[str]] = None) -> None:
     deprecated: list[tuple[str, str]] = [
         ("--salt", "--warksalt"),
         ("--hdr-au-usr", "--idp-h-usr"),
+        ("--idp-h-sep", "--idp-gsep"),
         ("--th-no-crop", "--th-crop=n"),
     ]
     for dk, nk in deprecated:
diff --git a/copyparty/authsrv.py b/copyparty/authsrv.py
index 612d661c..68e91659 100644
--- a/copyparty/authsrv.py
+++ b/copyparty/authsrv.py
@@ -824,7 +824,7 @@ class AuthSrv(object):
         if self.idp_usr_gh.get(uname) == gname:
             return False
 
-        gnames = [x.strip() for x in self.args.idp_h_sep.split(gname)]
+        gnames = [x.strip() for x in self.args.idp_gsep.split(gname)]
         gnames.sort()
 
         with self.mutex:
@@ -842,7 +842,7 @@ class AuthSrv(object):
                 self._reload()
                 return True
 
-        broker.ask("_reload", False).get()
+        broker.ask("_reload_blocking", False).get()
         return True
 
     def _map_volume_idp(
diff --git a/copyparty/svchub.py b/copyparty/svchub.py
index 80ead14c..8e496679 100644
--- a/copyparty/svchub.py
+++ b/copyparty/svchub.py
@@ -500,7 +500,7 @@ class SvcHub(object):
             if ptn:
                 setattr(self.args, k, re.compile(ptn))
 
-        for k in ["idp_h_sep"]:
+        for k in ["idp_gsep"]:
             ptn = getattr(self.args, k)
             if "]" in ptn:
                 ptn = "]" + ptn.replace("]", "")
@@ -706,6 +706,19 @@ class SvcHub(object):
             self.broker.reload()
             self.reloading = 0
 
+    def _reload_blocking(self, rescan_all_vols: bool = True) -> None:
+        while True:
+            with self.up2k.mutex:
+                if self.reloading < 2:
+                    self.reloading = 1
+                    break
+            time.sleep(0.05)
+
+        # try to handle multiple pending IdP reloads at once:
+        time.sleep(0.2)
+
+        self._reload(rescan_all_vols=rescan_all_vols)
+
     def stop_thr(self) -> None:
         while not self.stop_req:
             with self.stop_cond:
diff --git a/copyparty/up2k.py b/copyparty/up2k.py
index 1418e36d..37c698aa 100644
--- a/copyparty/up2k.py
+++ b/copyparty/up2k.py
@@ -836,10 +836,9 @@ class Up2k(object):
             self.log(msg, c=1)
 
         thr = None
-        if self.mtag:
+        if self.mtag and scan_vols:
             t = "online (running mtp)"
-            if scan_vols:
-                thr = Daemon(self._run_all_mtp, "up2k-mtp-scan", (gid,), r=False)
+            thr = Daemon(self._run_all_mtp, "up2k-mtp-scan", (gid,), r=False)
         else:
             self.pp = None
             t = "online, idle"
diff --git a/tests/util.py b/tests/util.py
index 0d243146..3230b629 100644
--- a/tests/util.py
+++ b/tests/util.py
@@ -146,7 +146,7 @@ class Cfg(Namespace):
             E=E,
             dbd="wal",
             fk_salt="a" * 16,
-            idp_h_sep=re.compile("[|:;+,]"),
+            idp_gsep=re.compile("[|:;+,]"),
             lang="eng",
             log_badpwd=1,
             logout=573,