When using the Counter PD, the first annotation has value "1" and spans from the beginning of the data to the first relevant signal change. My expectation would be that the first annotation (with value "1") begins at the first relevant signal change and ends at the second relevant signal change, where the annotation with value "2" begins.
The recent change was motivated by bug 1210. Also see the source code comment on _any_ choice of where to start the annotation being as arbitrary or valid as any other choice would be. https://sigrok.org/gitweb/?p=libsigrokdecode.git;a=blob;f=decoders/counter/pd.py;h=798fb3a7fc8aa2b4cbc15cc1bed26949ac37c975;hb=HEAD#l105 Whoever comes up with a semantics that matches more users' expectations is free to change the implementation. The spot which needs adjustment is identified above, the change might be obvious or straight forward. I don't mind. Go ahead. Note that the behaviour is more intuitive in the absence of RESET before the first edge of interest.
Of course the _presence_ of RESET avoids the observed unexpected behaviour in that specific exceptional situation. Just for the record.