I went on to Scotland's People, happening to have some unused Credits from a thwarted line.
I first tried for James Bruce in the 1871 Census; and he turned up without problem, including VIEWing and Downloading the Scanned IMAGE, "for the record".
That Image does have Robert and the expected others on it. No page splitting or such-like to confuse the issue.
I then tried for his father, Robert Bruce.
Again no problems; and the Search Index output included that I had VIEWED the Image, so up-to-date within the minute or so.
I did not try for any of the rest of the family, assuming that having found Robert particularly, the others should follow in.
So back to Find My Past.
"Ah dinnae credit it!"
Robert came up without any problems in the simple 1871 Census Search, unlike yesterday.
Now to Ancestry.
Although I am registered on that site, I have made very little use of it.
I could not set parameters tight enough to produce either the single result hoped for; or very few results to make it easy to scan through.
I tried various sets of Search parameters for both Robert and James, individually and together, apparently tightening the requirements; but Ancestry kept coming back with too many results, almost as though it was ignoring the tighter parameters.
I would therefore ask you, Gordon, to re-try your Ancrstry 1871 Searches; and let us know what happens.