[Windows Mobile Software Development] zard:
I've done further test since and I'm getting something rather consistently. Hope I can remember correctly the sequence.

1. Slide to FB tab then slide to RSS Tab. Tab shows "No updates and events".

2. Click on left softkey, screen remains the same.

3. By default, registry for "RSSFeed.FeedDataStore" is set to "\Storage Card\Program Files\RSS Hub\ChannelData\".

4. RSS Tab, trigger Read Data - RSSUtil.exe error

5. RSS Tab, trigger List Channels - ##Invalid/No file at :\Storage Card\Program Files\RSS Hub\ChannelData\ Channels.opml

6. Start RSS Hub, select Channels, Refresh. Close RSS Hub.

7. Delete all files from "\Storage Card\Program Files\RSS Hub\ChannelData\".

8. Copy files from "\Program Files\RSS Hub\ChannelData\" to "\Storage Card\Program Files\RSS Hub\ChannelData\".

9. Repeat steps (1) and (2). Same results.

10. RSS Tab, trigger Read Data - ##Invalid/No file at :\Storage Card\Program Files\RSS Hub\ChannelData\ Ch160.xml

11. RSS Tab, trigger List Channels - RSSUtil.exe error

12. Change "RSSFeed.FeedDataStore" from "\Storage Card\Program Files\RSS Hub\ChannelData\" to \Program Files\RSS Hub\ChannelData\".

13. Repeat steps (1) and (2). Same results.

14. RSS Tab, trigger Read Data - ##Invalid/No file at :\Storage Card\Program Files\RSS Hub\ChannelData\ Ch160.xml

15. RSS Tab, trigger List Channels - RSSUtil.exe error

16. Change "RSSFeed.FeedDataStore" from "\Program Files\RSS Hub\ChannelData\" to \Storage Card\Program Files\RSS Hub\ChannelData\".

17. Copied test data into "\Storage Card\Program Files\RSS Hub\ChannelData\"

18. Slide to FB tab then slide to RSS Tab. Tab shows "No updates and events".

19. Click on left softkey, screen remains the same.

20. RSS Tab, trigger Read Data - RSSUtil.exe error

21. RSS Tab, trigger List Channels - RSSUtil.exe error

At this point, it is consistent that RSSUTil.exe can't read both test data and RSS Hub data.

22. RSS Tab, trigger Test Data. Slide Tab to other tab, then back to RSS Tab. Tab shows Test Data feeds without icons.

23. RSS Tab, trigger Read Data. Tab screen remains the same. Slide Tab to other tab, then back to RSS Tab. Icons have been populated.

24. RSS Tab, trigger List Channels. Slide Tab to other tab, then back to RSS Tab - Tab screen shows RSS hub feeds.

25. Change "RSSFeed.FeedDataStore" from "\Storage Card\Program Files\RSS Hub\ChannelData\" to \Program Files\RSS Hub\ChannelData\".

26. Start RSS Hub, select Channels, add new Channel. Refresh.

27. RSS Tab, no change of the number of feeds.

27. RSS Tab, trigger List Channels. No change of the number of feeds.

28. Slide away from RSS Tab to other tab, slide back to RSS Tab. Tab screen shows all feeds including new feeds.

29. Did steps (26) to (28) but instead of adding, I deleted one feed. Result was consistent.

At this point, I don't think I had solved the RSSUtil.exe error as yet. Trying NetCF2 and NetCF3 (from mike2nl) can't even get into Debug Page. All testing now is using NetCF 3.7.

All the above was tested on 24631 build, Manila 2016. I can confirm that the above was consistent when my rom was 24631, Manila 2018.

Conclusion is RSSUtil cannot read the feeds, so registry don't have the feeds entry. After I populated with test data, the test data feeds entries was inside registry. After that, by doing List Channels and shifting of RSS Tab away from RSS Tab to other Tab and back again, I can see my feeds.

I'm going to try using stock WM build 21887 but cooked by myself, same lots of ext packages of the Cookie 24631 build I just used and see if it solves the RSSUtil.exe error (I don't think it will help). Will be also trying Energy ROM Topaz 23127 Cookie, 28 Aug (meltwater's rom is of same date and cookie, except it is HD version, seen in meltwater's signature).

Update:

I did exactly the same test above on Energy Topaz 23127 Cookie, 28 Aug and got the same result as the above. Looks like the RSSUtil.exe needs to be look into in further detail.