I have been using the browser based version, as cumbersome as it is, and many messages are not synced with the phone app.  
FYI, now messages are disappearing from the browser on the web verison (on htis website).
@vzw_customer_support  Community Manager Verizon is currently experiencing a wireless network issue with the Message+ desktop app. Our technicians are aware of this issue and are wo... Ver más...
@vzw_customer_support  Community Manager Verizon is currently experiencing a wireless network issue with the Message+ desktop app. Our technicians are aware of this issue and are working to resolve it quickly. Thank you for your patience during this time. AnnaG_VZW  Any idea on a timeline?
"@vzw_@vzw_customer_support wrote: So sorry to hear about the issues with Message+, HeidiMcCullough. I know how handy this feature is and I'm happy to help explain what is going on to clear up wh... Ver más...
"@vzw_@vzw_customer_support wrote: So sorry to hear about the issues with Message+, HeidiMcCullough. I know how handy this feature is and I'm happy to help explain what is going on to clear up why you are having these confusing experiences. The Message+ Verizon Messages - Windows Desktop application is not compatible with Windows 10 computers. The Windows messaging client for Verizon messages is being temporarily removed to prevent syncing issues and customers are able to utilize the messaging web client as a windows alternative. http://spr.ly/6603ENVyJ The Message+ team is aware and working on a resolution. RyanM_VZW"  Wow.  The first post on this thread was in March.  5 Months later, this is all you have?  You should be getting us a month's credit of service for all of the customers' time you've been wasting on this issue.  Terrible.   
jav6,   With all due respect, it's clear that the root cause of the problem hasn't been identified here and contacts syncing may in fact be a related issue.  I'm just adding info to the disc... Ver más...
jav6,  With all due respect, it's clear that the root cause of the problem hasn't been identified here and contacts syncing may in fact be a related issue.  I'm just adding info to the discussion and don't see it as sidetracking anything.  It's certainly not side tracking the stellar efforts demonstrated by Verizon thus far.
Also, my contacts don't sync properly either.  They never really have.  A few names do, but most don't.  Looking through the forum, syncing on the Windows 10 app has been a problem since 2016.  I hav... See more...
Also, my contacts don't sync properly either.  They never really have.  A few names do, but most don't.  Looking through the forum, syncing on the Windows 10 app has been a problem since 2016.  I have had minor issues syncing since about then, but I got most of my messages at least.  Now, it doesn't work at all.  I recevied 1 message on the Windows 10 app today vs about 25 on my phone.
So now, the Windows 10 desktop app is not receiving any messages.  When I send from the the desktop, they do not show up on my phone, but it seems like they are received on the other end becasue I've... Ver más...
So now, the Windows 10 desktop app is not receiving any messages.  When I send from the the desktop, they do not show up on my phone, but it seems like they are received on the other end becasue I've been getting replies. Syncing on the Windows 10 app has been sketchy for a long time.  It doesn't seem like Verizon is taking the issue seriously at all.  
I reported the bug on the phone app, but there is no way to do it on the Windows 10 desktop app.   The Windows 10 app doesn't sync properly. Sometimes it works and syncs fine, all the messages are t... Ver más...
I reported the bug on the phone app, but there is no way to do it on the Windows 10 desktop app.  The Windows 10 app doesn't sync properly. Sometimes it works and syncs fine, all the messages are the same across devices. Other times some messages sent on the Windows 10 app don't show on my phone and some sent from my phone don't show on the Windows 10 app. Today seems even worse where most of the phone messages are not syncing with the app and vice versa. I tried reinstalling the Windows 10 app and no luck.
I'm also having the same issue and would like to know when there is a resolution.  
I have had this issue for at least a year, probably two.  Sometimes it works and syncs fine, all the messages are the same across devices.  Other times some messages sent on the Windows 10 app don't ... Ver más...
I have had this issue for at least a year, probably two.  Sometimes it works and syncs fine, all the messages are the same across devices.  Other times some messages sent on the Windows 10 app don't show on my phone and some sent from my phone don't show on the Windows 10 app.  Today seems even worse where most of the phone messages are not syncing with the app and vice versa.  I tried reinstalling the Windows 10 app and no luck.
Export your Google contacts and upload them in your Verizon account.