Is there a way to check installed EVOK version? Didn't find any in evok.log (with DEBUG level). If you saying it was fixed recently, I might just have a problem with updating Evok or so. Will investigate with another UniPi device.

Downloaded this one: https://github.com/UniPiTechnology/evok/archive/v2.0.5b.zip

Trying to change digital input couter mode either to enabled or disabled returns success, but counter mode is not changed.

Invoke-RestMethod -Method POST -Uri http://10.3.2.65:8080/json/di/1_01 -ContentType application/json -Body '{"counter_mode":"disabled"}'

Success response:

{"status": "success", "data": {"counter_modes": ["Enabled", "Disabled"], "glob_dev_id": 1, "modes": ["Simple", "DirectSwitch"], "value": 0, "circuit": "1_01", "debounce": 754, "counter": 48, "counter_mode": "Enabled", "dev": "input", "mode": "Simple"}}

Checked if counter mode changed using UniPi Control Panel web and API call to get state.
Changing 'Debounce' or 'Counter' works OK.

API call is case-sensitive in strange way. Calling with 'Disabled' fails:
(despite it should be correct by doc: https://evok-6.api-docs.io/1.05/json/change-digital-input-state-json)

Invoke-RestMethod -Method POST -Uri http://10.3.2.65:8080/json/di/1_01 -ContentType application/json -Body '{"counter_mode":"Disabled"}'

returns BadRequest:

{"status": "fail", "data": "u'Disabled' is not one of ['disabled']\n\nFailed validating 'enum' in schema['properties']['counter_mode']:\n    {'enum': ['disabled'], 'type': 'string'}\n\nOn instance['counter_mode']:\n    u'Disabled'"}

I do have exactly same problem as described when installing Evok on UniPi Neuron with Rasbian Lite using steps here https://github.com/UniPiTechnology/evok#installation-process-for-the-20-evok-version