I just installed the latest nightly packages and now the problem has vanished. I am able to take exposures without the error message about streaming being active.

Thank you for testing.

FWIW, here is what was installed (and what packages were replaced):
Preparing to unpack .../libindi-data_1.7.2~201805011333~ubuntu16.04.1_all.deb .. .
Unpacking libindi-data (1.7.2~201805011333~ubuntu16.04.1) over (1.7.2~201804281327~ubuntu16.04.1) ...
Preparing to unpack .../libindi1_1.7.2~201805011333~ubuntu16.04.1_amd64.deb ...
Unpacking libindi1:amd64 (1.7.2~201805011333~ubuntu16.04.1) over (1.7.2~201804281327~ubuntu16.04.1) ...
Preparing to unpack .../indi-bin_1.7.2~201805011333~ubuntu16.04.1_amd64.deb ...
Unpacking indi-bin (1.7.2~201805011333~ubuntu16.04.1) over (1.7.2~201804281327~ubuntu16.04.1) ...
Preparing to unpack .../kstars-bleeding_6%3a2.9.5+201804290320~ubuntu16.04.1_amd64.deb ...
Unpacking kstars-bleeding (6:2.9.5+201804290320~ubuntu16.04.1) over (6:2.9.5+201804222120~ubuntu16.04.1) ...
Preparing to unpack .../kstars-bleeding-dbg_6%3a2.9.5+201804290320~ubuntu16.04.1_amd64.deb ...
Unpacking kstars-bleeding-dbg (6:2.9.5+201804290320~ubuntu16.04.1) over (6:2.9.5
Preparing to unpack .../kstars-bleeding-data_6%3a2.9.5+201804290320~ubuntu16.04.1_all.deb ...
Unpacking kstars-bleeding-data (6:2.9.5+201804290320~ubuntu16.04.1) over (6:2.9.5+201804222120~ubuntu16.04.1) ...
Preparing to unpack .../fxload_1.0~201804231514~ubuntu16.04.1_amd64.deb ...
Unpacking fxload (1.0~201804231514~ubuntu16.04.1) over (1.0~201712271246~ubuntu16.04.1) ...
Preparing to unpack .../indi-eqmod_0.5~201805011334~ubuntu16.04.1_amd64.deb ...
Unpacking indi-eqmod (0.5~201805011334~ubuntu16.04.1) over (0.5~201804281327~ubuntu16.04.1) ...
Preparing to unpack .../indi-maxdomeii_1.3~201805011315~ubuntu16.04.1_amd64.deb ...
Unpacking indi-maxdomeii (1.3~201805011315~ubuntu16.04.1) over (1.3~201804230817~ubuntu16.04.1) ...
Unpacking libqhy (2.0.3+r3929~201805011334~ubuntu16.04.1) over (2.0.3+r3916~201804230749~ubuntu16.04.1) ...
Preparing to unpack .../indi-qhy_1.8~201805011315~ubuntu16.04.1_amd64.deb ...
Unpacking indi-qhy (1.8~201805011315~ubuntu16.04.1) over (1.8~201804231504~ubuntu16.04.1) ...
Preparing to unpack .../indi-sx_1.13~201805011334~ubuntu16.04.1_amd64.deb ...
Unpacking indi-sx (1.13~201805011334~ubuntu16.04.1) over (1.13~201804271333~ubuntu16.04.1) ...

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