TBMiner's dev runs crash constantly

[Boulder08]

Console shows this command running when RBMiner switches to a dev run:
TBMiner.exe --algo kawpow --hostname kawpow.auto.nicehash.com --port 9200 --wallet 3PfUUT1Tknfyd4SnYrEwwpUEAQEzWd2BuD --worker-name mpx --server-passwd x --cuda-devices [0] --api --api-port 36500 --no-ansi --no-cpu

A lot of these errors shown then:
PS>TerminatingError(): "Exception calling "Wait" with "1" argument(s): "One or more errors occurred. (No connection could be made because the target machine actively refused it. (127.0.0.1:36520))" --> One or more errors occurred. (No connection could be made because the target machine actively refused it. (127.0.0.1:36520))"

The miner usually crashes once or twice, then suddenly starts working normally.