BUG: Ignore_index on concat does not ignore index

[mvirag2000]

I have this line of code which works fine in pandas 1.1.5 but not in 1.2.2:

vintable = pd.concat([vintable, data], join='inner', ignore_index=True)

I expect this to concatenate the rows, inner-join the columns, and then reindex - which it used to do in December. But now I get this error: "Reindexing only valid with uniquely valued Index objects." As I read the docs, it should not be looking at the index at all. So, I am fine sticking with 1.1.5 but I think is a bug ... TIA

[attack68]

a reproducible code snippet is needed to debug.

related to #39882 ?

[MarcoGorelli]

Hi @mvirag2000 - closing for now, will reopen if you include a reproducible example