ERGO Stratum: Block 615914 submission failed with: Invalid block mined: requirement failed: h(f) < b condition not met
**Describe the bug**
We have experienced this error three times now, from different stratum and different node combinations.  

On Miningcore stratum:

```
[2021-11-09 19:59:19.9642] [I] [ergo1] Submitting block 615914 []
[2021-11-09 19:59:20.4041] [W] [ergo1] Block 615914 submission failed with: Invalid block mined: requirement failed: h(f) < b condition not met
```

On the Ergo node:

```
06:59:20.308 INFO  [ctor.default-dispatcher-7] s.c.n.PeerConnectionHandler - Received message MessageSpec(55: Inv) from ConnectionId(remote=/93.123.180.164:9030, local=/10.1.2.4:43966, direction=Outgoing)
06:59:20.365 INFO  [tor.default-dispatcher-14] o.e.m.CandidateGenerator - New block mined, header: Header({"extensionId":"f24752386c96881c6177dd21eb6334041fcb9817ecf0d8004887165bf53d8beb","difficulty":"2076938810163200","votes":"000000","timestamp":1636459156974,"size":220,"stateRoot":"e3eb8495652d771314767d130855933b7e1b31107012399eacc35fcc86d0422617","height":615929,"nBits":117924087,"version":2,"id":"82484bb06abe5eb8edba97f887be953e20a2f35ac192cab294f060afcb73bcb9","adProofsRoot":"fd66557beeac91a49d7ee8aae253bd6946e1542223e23986c352f6d097ce903d","transactionsRoot":"89bfe51466e5172383c39a2fd913cea30794a94d9686d38abe0a8bc07398032b","extensionHash":"eb715ad70c258b497aaa007c920b20b22fd766a4681e3162fc04ef44cd63af29","powSolutions":{"pk":"0302122c332fd4e3c901f045ac18f559dcecf8dc61f6f94fbb34d0c7c3aac71fb7","w":"0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798","n":"a0b3655c998b6444","d":0},"adProofsId":"e8d0b10e86af6e9b8218d9b2fb8a4e79cdd5dede70d3a02f7405f1f2f6135324","transactionsId":"787727cb8dfda03a2467b31e13b86eba1e7a89b7cc33f1c384f68c1f6ba42db2","parentId":"d92695d75e26644c4dee1f3fe7eb98dc56799b850223f1107f470545660845bc"})
```


**To Reproduce**
Not sure how to reproduce this.

**Expected behavior**

**Screenshots**
See above

**OS**
 This is on Ubuntu 20.04

**Additional context**
Multiple stratum and nodes deployed, persisting to same Postgresql back end.  Stratum nodes are paired with their own Nodes.  Nodes have same pool wallet loaded, same API key used.