Heap profile dump showing zeroes.

I am trying to get the heap profile dump but I am seeing zeros throughout.

I built jemalloc with the following configuration
./configure --enable-prof --disable-fill --disable-cache-oblivious --enable-prof-libgcc --with-malloc-conf=prof:true,prof_active:true,lg_prof_interval:30,lg_prof_sample:20,narenas:default,narenas_ratio:0.5,tcache_max:4096,tcache_nslots_small_max:2000,tcache_nslots_large:512,background_thread:true,metadata_thp:auto,mutex_max_spin:1000,dirty_decay_ms:5000,muzzy_decay_ms:0

and am setting environment variable - MALLOC_CONF as follows
MALLOC_CONF=prof_active:true,prof:true,lg_prof_interval:30,lg_prof_sample:20

This is the heap profile sample.

7f6fd71d6000-7f6fdc5d6000 rw-p 00000000 00:00 0
7f6fdc5d6000-7f6fdc5d7000 ---p 00000000 00:00 0
7f6fdc5d7000-7f6fdcdd7000 rw-p 00000000 00:00 0
7f6fdcdd7000-7f6fdfe57000 rw-p 00000000 00:00 0
7f6fdfe57000-7f6fdfe58000 ---p 00000000 00:00 0
7f6fdfe58000-7f6fe0658000 rw-p 00000000 00:00 0
7f6fe0658000-7f6fe0659000 ---p 00000000 00:00 0
7f6fe0659000-7f6fe0e59000 rw-p 00000000 00:00 0
7f6fe0e59000-7f6fe1e59000 rw-p 00000000 00:00 0
7f6fe1e59000-7f6fe1e5a000 ---p 00000000 00:00 0

Start by reproducing the heap profile with the reported jemalloc configure options and MALLOC_CONF values. Compare the generated output with the supplied memory-map sample and investigate the profiling configuration and dump path. Done means identifying why the profile contains only zeroes and documenting or fixing the behavior with a verified non-zero dump.