Timestamp always uses SHA1 for hash algorithm and ignores HashAlgo settings

After SHAttered we are attempting to change the default hash algorithm for timestamps in Adobe Reader DC 2015.020.20042 from SHA1 to SHA256.

All attempts to override the default setting have failed and the resulting hash for the timestamp signature as displayed in Signature Properties, Advanced Properties is always SHA1.

I've used the following registry settings according to the documentation in HKCU\Software\Adobe\Acrobat Reader\DC\Security\cASPKI\cAdobe_TSPProvider with several different timestamp servers:

sHashAlgo

iHashAlgo

If I set an invalid value Acrobat displays an error message "Unsupported hash algorithm" which indicates that the settings are being read.

Appreciate any help,

Nick