5.6.0-050600rc4-generic
Same behaviour:

First time works:
[  122.113542] PM: suspend entry (s2idle)
[  122.118823] Filesystems sync: 0.005 seconds
[  122.120954] Freezing user space processes ... (elapsed 0.002 seconds) done.
[  122.123333] OOM killer disabled.
[  122.123334] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
[  122.124606] printk: Suspending console(s) (use no_console_suspend to debug)
[  122.125072] wlp0s20f3: deauthenticating from 18:d6:c7:61:95:c2 by local choice (Reason: 3=DEAUTH_LEAVING)
[  122.230038] e1000e: EEE TX LPI TIMER: 00000011
[  122.345108] ACPI: EC: interrupt blocked
[  138.117673] ACPI: EC: interrupt unblocked
[  140.917449] iwlwifi 0000:00:14.3: Applying debug destination EXTERNAL_DRAM
[  141.031854] iwlwifi 0000:00:14.3: Applying debug destination EXTERNAL_DRAM
[  141.096775] iwlwifi 0000:00:14.3: FW already configured (0) - re-configuring
[  143.796468] e1000e 0000:00:1f.6 enp0s31f6: PHY Wakeup cause - Unicast Packet
[  144.466557] e1000e 0000:00:1f.6 enp0s31f6: Hardware Error
[  145.195597] OOM killer enabled.
[  145.195597] Restarting tasks ... done.
[  145.213016] mei_hdcp 0000:00:16.0-b638ab7e-94e2-4ea2-a552-d1c54b627f04: bound 0000:00:02.0 (ops i915_hdcp_component_ops [i915])
[  145.239043] PM: suspend exit

Second time fails to suspend:
[  169.696561] PM: suspend entry (s2idle)
[  169.734111] Filesystems sync: 0.037 seconds
[  169.734688] Freezing user space processes ... (elapsed 0.002 seconds) done.
[  169.736790] OOM killer disabled.
[  169.736791] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
[  169.738032] printk: Suspending console(s) (use no_console_suspend to debug)
[  169.738318] wlp0s20f3: deauthenticating from 18:d6:c7:61:95:c2 by local choice (Reason: 3=DEAUTH_LEAVING)
[  169.839564] e1000e: EEE TX LPI TIMER: 00000011
[  171.730682] PM: pci_pm_suspend(): e1000e_pm_suspend+0x0/0x80 [e1000e] returns -2
[  171.730685] PM: dpm_run_callback(): pci_pm_suspend+0x0/0x170 returns -2
[  171.730687] PM: Device 0000:00:1f.6 failed to suspend async: error -2
[  172.997917] PM: Some devices failed to suspend, or early wake event detected
[  173.010160] iwlwifi 0000:00:14.3: Applying debug destination EXTERNAL_DRAM
[  173.126554] iwlwifi 0000:00:14.3: Applying debug destination EXTERNAL_DRAM
[  173.193691] iwlwifi 0000:00:14.3: FW already configured (0) - re-configuring
[  173.222986] OOM killer enabled.
[  173.222987] Restarting tasks ... 
[  173.235209] mei_hdcp 0000:00:16.0-b638ab7e-94e2-4ea2-a552-d1c54b627f04: bound 0000:00:02.0 (ops i915_hdcp_component_ops [i915])
[  173.235267] done.
[  173.266890] PM: suspend exit

Suspend works with eoan's 5.3.0-18-generic (same system, just booted into the old kernel):

First time successful:
[   66.725822] PM: suspend entry (s2idle)
[   66.731748] Filesystems sync: 0.005 seconds
[   66.732769] Freezing user space processes ... (elapsed 0.002 seconds) done.
[   66.735102] OOM killer disabled.
[   66.735103] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
[   66.736358] printk: Suspending console(s) (use no_console_suspend to debug)
[   66.737562] wlp0s20f3: deauthenticating from 18:d6:c7:61:95:c2 by local choice (Reason: 3=DEAUTH_LEAVING)
[   66.842558] pcieport 0000:06:04.0: pciehp: pcie_do_write_cmd: no response from device
[   66.842582] pcieport 0000:06:01.0: pciehp: pcie_do_write_cmd: no response from device
[   66.843126] e1000e: EEE TX LPI TIMER: 00000011
[   81.464128] iwlwifi 0000:00:14.3: Applying debug destination EXTERNAL_DRAM
[   81.582688] iwlwifi 0000:00:14.3: Applying debug destination EXTERNAL_DRAM
[   81.650014] iwlwifi 0000:00:14.3: FW already configured (0) - re-configuring
[   82.278399] OOM killer enabled.
[   82.278399] Restarting tasks ... done.
[   82.329029] PM: suspend exit

Second time successful too:
[  110.896082] PM: suspend entry (s2idle)
[  110.903315] Filesystems sync: 0.007 seconds
[  110.904398] Freezing user space processes ... (elapsed 0.002 seconds) done.
[  110.906958] OOM killer disabled.
[  110.906958] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
[  110.908232] printk: Suspending console(s) (use no_console_suspend to debug)
[  110.909122] wlp0s20f3: deauthenticating from 18:d6:c7:61:95:c2 by local choice (Reason: 3=DEAUTH_LEAVING)
[  111.010349] pcieport 0000:06:04.0: pciehp: pcie_do_write_cmd: no response from device
[  111.010410] pcieport 0000:06:01.0: pciehp: pcie_do_write_cmd: no response from device
[  111.010499] e1000e: EEE TX LPI TIMER: 00000011
[  137.062899] iwlwifi 0000:00:14.3: Applying debug destination EXTERNAL_DRAM
[  137.180784] iwlwifi 0000:00:14.3: Applying debug destination EXTERNAL_DRAM
[  137.248212] iwlwifi 0000:00:14.3: FW already configured (0) - re-configuring
[  137.880444] OOM killer enabled.
[  137.880444] Restarting tasks ... done.
[  137.927342] PM: suspend exit