ndscope not doing anything if multiple channels are selected from the dialog

If more than one channel is selected in ndscope, it just makes all buttons and fields gray and does not seem to make any attempts to connect to the server. In the following example, two channels -- B1:ACT-PDS_SmarActHead_OUT_DQ and B1:ACT-PDS_SmarActHead2_OUT_DQ -- were selected from the channel selection dialog.

Output to the terminal:

cdsadmin@peapsy:~$ LOG_LEVEL=debug ndscope
TEMPLATE: created template from channel list
SCOPE: version 0.15.1
SCOPE: server 147.188.32.246:8088
DATA : RESET
DATA : data store initialized
SCOPE: creating plot {}...
SCOPE: connecting plot 0...
SCOPE: set window: -2 0
SCOPE: loading template...
SCOPE: clearing plots...
SCOPE: removing plot: (0, 0)
SCOPE: creating plot {'row': 0, 'col': 0, 'colspan': 1}...
SCOPE: connecting plot 0...
SCOPE: t0=None, window=(-2, 0)
SCOPE: START
SCOPE: set window: -2 0
DATA : START ONLINE
DATA : STOP
DATA : RESET
DATA : CMD: find_channels {}
NDS  : find_channels(**{'channel_glob': '*', 'channel_type_mask': 39})
DATA : CMD: find_channels {}
DATA : BUSY: find_channels
DATA : REQUEST: raw (1330965311.505077, 1330965313.505077)
DATA : channel list received: 2902 channels
SCOPE: building channel models...
DATA : DONE: ('find_channels', None)
SCOPE: channel select dialog ready.
SCOPE: added channel: B1:ACT-PDS_SmarActHead_OUT_DQ
DATA : CHANNEL B1:ACT-PDS_SmarActHead_OUT_DQ 1
SCOPE: added channel: B1:ACT-PDS_SmarActHead2_OUT_DQ
DATA : CHANNEL B1:ACT-PDS_SmarActHead2_OUT_DQ 1

Additional information:

• The issue is reproduced with any channels types (fast and slow, DQ and non-DQ);
• The issue is reproduced when selecting two or more channels from the dialog; ndscope works as expected if only one channel is selected from the dialog
• ndscope was installed from the Debian package through apt
• ndscope version is 0.15.1
• The issue is reproduced on different workstations running Debian 10/KDE, Debian 11/KDE, Debian 11/xfce4
• ndscope works fine if the channels are requested from the command line instead, in this case the plots are shown as expected and NDS requests appear in the log (see below).

Output to the terminal if channels are selected from command line (click to expand/fold)

cdsadmin@peapsy:~$ LOG_LEVEL=debug ndscope B1:ACT-PDS_SmarActHead_OUT_DQ B1:ACT-PDS_SmarActHead2_OUT_DQ
TEMPLATE: created template from channel list
SCOPE: version 0.15.1
SCOPE: server 147.188.32.246:8088
DATA : RESET
DATA : data store initialized
SCOPE: creating plot {}...
SCOPE: connecting plot 0...
SCOPE: set window: -2 0
SCOPE: loading template...
SCOPE: clearing plots...
SCOPE: removing plot: (0, 0)
SCOPE: creating plot {'row': 0, 'col': 0, 'colspan': 1}...
SCOPE: connecting plot 0...
SCOPE: added channel: B1:ACT-PDS_SmarActHead_OUT_DQ
DATA : CHANNEL B1:ACT-PDS_SmarActHead_OUT_DQ 1
SCOPE: creating plot {'row': 1, 'col': 0, 'colspan': 1}...
SCOPE: connecting to plot 0...
SCOPE: added channel: B1:ACT-PDS_SmarActHead2_OUT_DQ
DATA : CHANNEL B1:ACT-PDS_SmarActHead2_OUT_DQ 1
SCOPE: t0=None, window=(-2, 0)
SCOPE: START
SCOPE: set window: -2 0
DATA : START ONLINE
DATA : STOP
DATA : RESET
DATA : CMD: online {'trend': 'raw', 'channels': ['B1:ACT-PDS_SmarActHead_OUT_DQ', 'B1:ACT-PDS_SmarActHead2_OUT_DQ']}
SCOPE: crosshair disabled
SCOPE: time axis mode: relative
NDS  : iterate(**{'channels': ['B1:ACT-PDS_SmarActHead_OUT_DQ', 'B1:ACT-PDS_SmarActHead2_OUT_DQ'], 'stride': -1, 'params':  >})
DATA : CMD: find_channels {}
NDS  : find_channels(**{'channel_glob': '*', 'channel_type_mask': 39})
DATA : REQUEST: raw (1330965252.639013, 1330965254.639013)
DATA : CMD: extend {'trend': 'raw', 'channels': ['B1:ACT-PDS_SmarActHead_OUT_DQ', 'B1:ACT-PDS_SmarActHead2_OUT_DQ'], 'start_end': (1330965251, 1330965256)}
DATA : BUSY: no extend while online
DATA : channel list received: 2902 channels
SCOPE: building channel models...
DATA : DONE: ('find_channels', None)
SCOPE: channel select dialog ready.
DATA : CMD: extendleft {'trend': 'raw', 'channels': ['B1:ACT-PDS_SmarActHead_OUT_DQ', 'B1:ACT-PDS_SmarActHead2_OUT_DQ'], 'start_end': (1330965251.9253612, 1330965254.0625)}
NDS  : fetch(**{'channels': ['B1:ACT-PDS_SmarActHead_OUT_DQ', 'B1:ACT-PDS_SmarActHead2_OUT_DQ'], 'gps_start': 1330965251, 'gps_stop': 1330965255, 'params':  >})
/usr/lib/python3/dist-packages/pyqtgraph/graphicsItems/PlotCurveItem.py:131: RuntimeWarning: All-NaN slice encountered
  b = (np.nanmin(d), np.nanmax(d))
DATA : DONE: ('extendleft-raw', None)
QBasicTimer::start: QBasicTimer can only be used with threads started with QThread
QBasicTimer::start: QBasicTimer can only be used with threads started with QThread
QBasicTimer::start: QBasicTimer can only be used with threads started with QThread
QBasicTimer::start: QBasicTimer can only be used with threads started with QThread
QBasicTimer::start: QBasicTimer can only be used with threads started with QThread