asynFloat64 never finishes processing in IOCTestFramework

This issue occurs with motorExtensions at commit 692e494.

- Get the commit of motorExtensions above
- Run the oscillatingCollimator tests in the IOC test framework
- Note that the tests fail

The tests above fail because the values for the set PVs are never pushed to the subsequent records. On inspection, the PACT field of PVs such as ANGLE:SP never return to 0. The workaround we used was to convert these to "Soft Channel"s in simulation mode at run time. Notably this causes exceptions to be output during the run of the collimator tests, although it does not cause a failure.

We tried setting the PVs in question into simulation mode with a suitable simulation output location but it did not improve the behaviour.

Another curious behaviour is that, after converting the records to Soft Channels, forward linking from ANGLE:SP to DIST:PART:SP still didn't work within the IOC Test Framework; the tests failed indicating the required values hadn't been forwarding. However, doing a caput from the command line worked fine and trigerred passing the value.

John nor I could explain away this behaviour. A working fix was eventually implemented for the oscillating collimator #2535 but we would like to understand why this occurred