Please check
https://github.com/wiredtiger/wiredtiger/blob/master/src/lsm/lsm_cursor.c#L677
clsm->chunks[i]->count = lsm_tree->chunk[i]->count;
should be
clsm->chunks[i]->count = lsm_tree->chunk[start_chunk + i]->count;
Please check
https://github.com/wiredtiger/wiredtiger/blob/master/src/lsm/lsm_cursor.c#L677
clsm->chunks[i]->count = lsm_tree->chunk[i]->count;
should be
clsm->chunks[i]->count = lsm_tree->chunk[start_chunk + i]->count;