Region Based algorithm dealiasing large areas of no aliasing with a blanket Vn

[CGLiesker]

The region-based dealiasing algorithm has worked well for our S-Band radar (we are specifically looking at event days with mesocyclones present), however, I have noticed on various timesteps for various case dates the following occurs where the algorithm provide a blanket velocity value (which appears to be the Nyquist value of 39.19 m/s) for echoes that do not have any dealiasing issues.
Here is an example of this issue:

I ran the algorithm with the following settings:
dealias_data = pyart.correct.dealias_region_based(
radar, interval_splits=4, skip_between_rays=5, skip_along_rays=5,
gatefilter=gatefilter,
rays_wrap_around=True, keep_original=True, vel_field="V")

Originally I used the default skip_between_rays/along_rays but reducing it to 5 each made a difference for some elevations and timesteps but did not fix all Some cases at least reduced the neighbouring echoes that were also initially affected). Decreasing it below 5 resulted in additional issues and did not fix for example the timestep provided above. I also tried increasing this value to for example 10, and the above example was no longer an issue however, the previous timestep then had this issue (at a different elevation) for a similar area (see below).

I have tried changing the intervals splits and various other parameters in the dealiasing function (including providing the Vn directly) but nothing seems to solve this issue. Any suggestions? Could there be a bug in the code or perhaps an issue with the data files themselves that could be causing this?