IdxCheck does not indicate index corruption problems.
 

The index area reached the 32/64 bit boundary.

An additional diagnostic option exists in 11.6/4 and later that allows identification if an index is hitting this problem.
If 11.6.4 or later is not available then identification can be done with the following steps however the fix to this problem REQUIRES upgrade to 11.6.4. or later.

Determine if you can reached the 32/64bit boundary issue in any index area using the following calculations:

1. - Run prostrct statistics <database name>
2. - Get the active blocks in the area
3. - Get the records per block defined for all areas containing indices
4. - Perform the following calculation

5. If the area has more blocks than the calculated Block_limit it is possible to encounter this problem.

To fix the problem perform the following steps:

1) Upgrade to the latest OpenEdge 11.7 to be able to run idxcheck with option 5.

2) Identify to which area the index block reported in error (4423) belong to since the table and indices were deleted using the idxblockreport command to list the blocks that form the index tree:

proutil <database> -C idxblockreport <index >

3) Run idxcheck with options O (this is the letter o not zero) and 5 for all indices:
Example:
proutil <database> -C idxcheck

Index Check Utility
===================

Select one of the following:
--------------------
All (a/A) - Choose all the indexes
Some (s/S) - Choose only some of the indexes
By Area (r/R) - Choose indexes in selected areas
By Schema (c/C) - Choose indexes by schema owners
By Table (t/T) - Choose indexes in selected tables
--------------------
Validation (o/O) - Change validation options
--------------------
Quit (q/Q)

Enter your selection:
o

Validation Options
----------------
1 - Validate physical consistency of index blocks
2 - Validate keys for each record
3 - Validate record for each key


4 - Validate key order
* 5 - Validate tree
6 - Validate index against free cluster
R - Reset error limit, current: 500
C - Continue to execute
Q - Quit

c
Select one of the following:
--------------------
All (a/A) - Choose all the indexes
Some (s/S) - Choose only some of the indexes
By Area (r/R) - Choose indexes in selected areas
By Schema (c/C) - Choose indexes by schema owners
By Table (t/T) - Choose indexes in selected tables
--------------------
Validation (o/O) - Change validation options
--------------------
Quit (q/Q)

Enter your selection:
a

______________

This option runs extremely fastand and will shows areas that have indices where the the specific 32/64 boundary issue exists:
Example:
IDXCHEK : (19005) Detected 32/64 dbkey mismatch for index <indexnum>, level <level num>, block <block num>.
IDXCHEK : (19006) An entry(entry number 1) has a 64 bit flag but points to a 32 bit DBKEY <dbkey>.

4) Rebuild all indices reported by idxcheck option 5.

Progress Article(s):
Defect: Database crashes with 8783 or 210 error due to index corruption.