After 3 weeks, starter is bubbling with no rise

I know this is a common problem, but after three weeks of Google searching and trying things I have found with no success...I thought I give this one more shot....

First off, my starters are about 5 years old. They are all AP flour/water starters and I store them in the fridge when not using them. Usually when I remove them from the fridge, I leave them out for several hours to warm up, then feed them on a 1:1:1 ratio for 2-3 days and they are back to bubbling and rising nicely. I have not baked bread in a while, but have consistently taken out my starters to feed them every couple of months to keep them alive. I have had great results with them until now. When the pandemic started, I thought this would be a great time to renew my starters and bake some bread. I took them out of the fridge as usual, but after several days I noticed bubbles, but no rise.

Things I have tried with no success:

To try to increase yeast, I took 1T starter, mixed it into 1/4 cup water and added 1T AP flour and left them out for a day. I then added another tablespoon of AP flour the next day to thicken it a bit and left it out for another day. I then added another tablespoon of AP flour the third day to thicken again and added a bit more water to make a stiff batter and left it out for another day. After each day, there were bubbles, but no rise.

So this week, I discarded most of my starter, leaving only about 1/4 cup, I added 1/4 flour and 3 T water. It bubbled nicely, smelled great, but no rise. Have done this for several days...same results.

What else can I try? I have to admit that up until now I have been pretty casual with my feedings...not weighing anything and just going on the feel of it. I am now desperate and ready to be more scientific about it. Thanks for your help!