Static Route entry unreachable

I have two hEX devices that have been working stably for a long time. Recently, I upgraded them to 7.18.2 and added a routing table to each, populating it with some route entries, basically copied from the dynamic entries. Did I configure something incorrectly?
Anything you can do to help would be great, thanks!

/routing/nexthop> print
Flags: R - REACHABLE
Columns: ADDRESS, SCOPE, TARGET-SCOPE, IMMEDIATE-GW.ADDRESS, IMMEDIATE-GW.WEIGH>
  ADDRESS     SCOPE  TA  IMMEDIATE-  I  IMMEDIATE-  IM  I  IMMEDIATE-  IM
R pppoe-out1     30  10  pppoe-out1  1  1788458157  18  0  4294967295  no
R bridge         10   5  bridge      1  3041712726  12  0  4294967295  no
R pppoe-out1     10   5  pppoe-out1  1  1788458157  18  0  4294967295  no
  pppoe-out1     30  10  pppoe-out1  1  1788458157  18  0  4294967295  no
  bridge         10   5  bridge      1  3041712726  12  0  4294967295  no
-- [Q quit|D dump|right]

/ip/route> print detail 
Flags: D - dynamic; X - disabled, I - inactive, A - active; 
c - connect, s - static, r - rip, b - bgp, o - ospf, i - is-is, d - dhcp, v - v>
H - hw-offloaded; + - ecmp 
   DAv   dst-address=0.0.0.0/0 routing-table=main gateway=pppoe-out1 
         immediate-gw=pppoe-out1 distance=1 scope=30 target-scope=10 
         vrf-interface=pppoe-out1 

   DAc   dst-address=192.168.88.0/24 routing-table=main gateway=bridge 
         immediate-gw=bridge distance=0 scope=10 target-scope=5 
         local-address=192.168.88.1%bridge 

   DAc   dst-address=x.x.x.x/32 routing-table=main gateway=pppoe-out1 
         immediate-gw=pppoe-out1 distance=0 scope=10 target-scope=5 
         local-address=x.x.x.x%pppoe-out1 

 0  Is   dst-address=0.0.0.0/0 routing-table=tttt gateway=pppoe-out1 
         immediate-gw=pppoe-out1 check-gateway=ping distance=1 scope=30 
         target-scope=10 suppress-hw-offload=no 

 1  Is   dst-address=192.168.88.0/24 routing-table=tttt gateway=bridge 
         immediate-gw=bridge check-gateway=ping distance=1 scope=10 
         target-scope=5 suppress-hw-offload=no

After reading some posts, I checked my IP addresses using /ip/address, and they look okay. There shouldn’t be an issue there because the default routes are working fine. The new routes I added are just in a separate, new routing table. The same setup worked perfectly on version 6.49, and all the static routes were reachable back then.

/ip/address> print
Flags: D - DYNAMIC
Columns: ADDRESS, NETWORK, INTERFACE
#   ADDRESS             NETWORK         INTERFACE 
;;; defconf
0   192.168.88.1/24     192.168.88.0    bridge    
1 D x.234.138.130/32  x.159.251.65  pppoe-out1

Can anyone provide some insight on this topic? I’m interested because I’ve encountered similar situations. If anyone has a solution or suggestions, please let me know. Thank you..

You night want to post your whole configuration, there may be some misconfiguration elsewhere, but why do you have check-gateway on those two routes?
I believe you can use check-gateway only if the gateway is an IP, not when it is an interface.