There's a bug in MovableType 3.2 which may result in "lost" comments after the upgrade. This happens mostly to people using MT with Berkeley DB, which (surprise, surprise) was also my case.
There is official solution yet, but luckily, there is quick patch by "seebs" which can take care of the problem:
*** 443,448 ****
--- 443,451 ----
for my $col (keys %$terms) {
my $range = $args->{range} && $args->{range}->{$col} &&
(ref $terms->{$col} eq 'ARRAY');
+ if (!defined $rec->{$col}) {
+ $rec->{$col} = 0;
+ }
next if $range &&
($rec->{$col} gt $terms->{$col}->[0]) &&
($rec->{$col} lt $terms->{$col}->[1]);
